21656877 has 16 divisors (see below), whose sum is σ = 32354112. Its totient is φ = 12769920.

The previous prime is 21656867. The next prime is 21656893. The reversal of 21656877 is 77865612.

It is not a de Polignac number, because 21656877 - 2⁶ = 21656813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656857) 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 15 ways as a sum of consecutive naturals, for example, 7648 + ... + 10089.

It is an arithmetic number, because the mean of its divisors is an integer number (2022132).

Almost surely, 2^21656877 is an apocalyptic number.

It is an amenable number.

21656877 is a deficient number, since it is larger than the sum of its proper divisors (10697235).

21656877 is a wasteful number, since it uses less digits than its factorization.

21656877 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17788.

The product of its digits is 141120, while the sum is 42.

The square root of 21656877 is about 4653.6949835588. The cubic root of 21656877 is about 278.7395598924.

The spelling of 21656877 in words is "twenty-one million, six hundred fifty-six thousand, eight hundred seventy-seven".