221473728 has 336 divisors, whose sum is σ = 792480000. Its totient is φ = 58931712.

The previous prime is 221473727. The next prime is 221473757. The reversal of 221473728 is 827374122.

221473728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×221473728² = 98101224388435968, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 221473692 and 221473701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221473727) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3753763 + ... + 3753821.

Almost surely, 2^221473728 is an apocalyptic number.

221473728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221473728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (396240000).

221473728 is an abundant number, since it is smaller than the sum of its proper divisors (571006272).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221473728 is a wasteful number, since it uses less digits than its factorization.

221473728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 90 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The square root of 221473728 is about 14881.9934148621. The cubic root of 221473728 is about 605.0260471904.

The spelling of 221473728 in words is "two hundred twenty-one million, four hundred seventy-three thousand, seven hundred twenty-eight".