21556960 has 24 divisors (see below), whose sum is σ = 50928696. Its totient is φ = 8622720.

The previous prime is 21556943. The next prime is 21556961. The reversal of 21556960 is 6965512.

It is a happy number.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67206 + ... + 67525.

It is an arithmetic number, because the mean of its divisors is an integer number (2122029).

Almost surely, 2^21556960 is an apocalyptic number.

21556960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21556960 is an abundant number, since it is smaller than the sum of its proper divisors (29371736).

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

21556960 is a wasteful number, since it uses less digits than its factorization.

21556960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134746 (or 134738 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 21556960 is about 4642.9473397832. The cubic root of 21556960 is about 278.3102311095.

It can be divided in two parts, 215 and 56960, that added together give a palindrome (57175).

The spelling of 21556960 in words is "twenty-one million, five hundred fifty-six thousand, nine hundred sixty".