21136656 has 20 divisors (see below), whose sum is σ = 54603152. Its totient is φ = 7045536.

The previous prime is 21136649. The next prime is 21136663. The reversal of 21136656 is 65663112.

It is an interprime number because it is at equal distance from previous prime (21136649) and next prime (21136663).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220126 + ... + 220221.

Almost surely, 2^21136656 is an apocalyptic number.

It is an amenable number.

21136656 is an abundant number, since it is smaller than the sum of its proper divisors (33466496).

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

21136656 is a wasteful number, since it uses less digits than its factorization.

21136656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440358 (or 440352 counting only the distinct ones).

The product of its digits is 6480, while the sum is 30.

The square root of 21136656 is about 4597.4619084882. The cubic root of 21136656 is about 276.4895742542.

Adding to 21136656 its reverse (65663112), we get a palindrome (86799768).

The spelling of 21136656 in words is "twenty-one million, one hundred thirty-six thousand, six hundred fifty-six".