221402720 has 96 divisors (see below), whose sum is σ = 652167936. Its totient is φ = 69004800.

The previous prime is 221402683. The next prime is 221402767. The reversal of 221402720 is 27204122.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 221402692 and 221402701.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3335 + ... + 21305.

It is an arithmetic number, because the mean of its divisors is an integer number (6793416).

Almost surely, 2^221402720 is an apocalyptic number.

221402720 is a gapful number since it is divisible by the number (20) 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 221402720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (326083968).

221402720 is an abundant number, since it is smaller than the sum of its proper divisors (430765216).

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

221402720 is a wasteful number, since it uses less digits than its factorization.

221402720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18004 (or 17996 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 221402720 is about 14879.6075217057. The cubic root of 221402720 is about 604.9613799540.

Adding to 221402720 its reverse (27204122), we get a palindrome (248606842).

It can be divided in two parts, 221402 and 720, that multiplied together give a triangular number (159409440 = T₁₇₈₅₅).

The spelling of 221402720 in words is "two hundred twenty-one million, four hundred two thousand, seven hundred twenty".