21545656 has 16 divisors (see below), whose sum is σ = 44070840. Its totient is φ = 9793440.

The previous prime is 21545653. The next prime is 21545663. The reversal of 21545656 is 65654512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545653) 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, 122331 + ... + 122506.

Almost surely, 2^21545656 is an apocalyptic number.

It is an amenable number.

21545656 is an abundant number, since it is smaller than the sum of its proper divisors (22525184).

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

21545656 is a wasteful number, since it uses less digits than its factorization.

21545656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244854 (or 244850 counting only the distinct ones).

The product of its digits is 36000, while the sum is 34.

The square root of 21545656 is about 4641.7298499590. The cubic root of 21545656 is about 278.2615759974.

It can be divided in two parts, 215456 and 56, that added together give a palindrome (215512).

The spelling of 21545656 in words is "twenty-one million, five hundred forty-five thousand, six hundred fifty-six".