21656135 has 12 divisors (see below), whose sum is σ = 26858664. Its totient is φ = 16762320.

The previous prime is 21656119. The next prime is 21656149. The reversal of 21656135 is 53165612.

It is not a de Polignac number, because 21656135 - 2⁴ = 21656119 is a prime.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21656098 and 21656107.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2552 + ... + 7058.

It is an arithmetic number, because the mean of its divisors is an integer number (2238222).

Almost surely, 2^21656135 is an apocalyptic number.

21656135 is a deficient number, since it is larger than the sum of its proper divisors (5202529).

21656135 is an equidigital number, since it uses as much as digits as its factorization.

21656135 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4574 (or 4543 counting only the distinct ones).

The product of its digits is 5400, while the sum is 29.

The square root of 21656135 is about 4653.6152612781. The cubic root of 21656135 is about 278.7363764984.

The spelling of 21656135 in words is "twenty-one million, six hundred fifty-six thousand, one hundred thirty-five".