21357636 has 24 divisors (see below), whose sum is σ = 51442944. Its totient is φ = 6889440.

The previous prime is 21357619. The next prime is 21357697. The reversal of 21357636 is 63675312.

It is a super-2 number, since 2×21357636² = 912297231016992, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21357597 and 21357606.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28335 + ... + 29078.

It is an arithmetic number, because the mean of its divisors is an integer number (2143456).

Almost surely, 2^21357636 is an apocalyptic number.

It is an amenable number.

21357636 is an abundant number, since it is smaller than the sum of its proper divisors (30085308).

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

21357636 is a wasteful number, since it uses less digits than its factorization.

21357636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57451 (or 57449 counting only the distinct ones).

The product of its digits is 22680, while the sum is 33.

The square root of 21357636 is about 4621.4322455274. The cubic root of 21357636 is about 277.4497855736.

The spelling of 21357636 in words is "twenty-one million, three hundred fifty-seven thousand, six hundred thirty-six".