221997840 has 160 divisors (see below), whose sum is σ = 725953536. Its totient is φ = 56010240.

The previous prime is 221997829. The next prime is 221997847. The reversal of 221997840 is 48799122.

221997840 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 221997792 and 221997801.

It is not an unprimeable number, because it can be changed into a prime (221997847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 722967 + ... + 723273.

Almost surely, 2^221997840 is an apocalyptic number.

221997840 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 221997840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (362976768).

221997840 is an abundant number, since it is smaller than the sum of its proper divisors (503955696).

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

221997840 is a wasteful number, since it uses less digits than its factorization.

221997840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 477 (or 471 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 42.

The square root of 221997840 is about 14899.5919407211. The cubic root of 221997840 is about 605.5029308451.

The spelling of 221997840 in words is "two hundred twenty-one million, nine hundred ninety-seven thousand, eight hundred forty".