21756560 has 40 divisors (see below), whose sum is σ = 57811776. Its totient is φ = 7459200.

The previous prime is 21756557. The next prime is 21756563. The reversal of 21756560 is 6565712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21756557) and next prime (21756563).

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21756563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18866 + ... + 19985.

Almost surely, 2^21756560 is an apocalyptic number.

21756560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21756560 is an abundant number, since it is smaller than the sum of its proper divisors (36055216).

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

21756560 is a wasteful number, since it uses less digits than its factorization.

21756560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38871 (or 38865 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 21756560 is about 4664.3927793444. The cubic root of 21756560 is about 279.1665693423.

The spelling of 21756560 in words is "twenty-one million, seven hundred fifty-six thousand, five hundred sixty".