21557356 has 12 divisors (see below), whose sum is σ = 37966768. Its totient is φ = 10709712.

The previous prime is 21557351. The next prime is 21557383. The reversal of 21557356 is 65375512.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21557351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16536 + ... + 17791.

Almost surely, 2^21557356 is an apocalyptic number.

It is an amenable number.

21557356 is a deficient number, since it is larger than the sum of its proper divisors (16409412).

21557356 is a wasteful number, since it uses less digits than its factorization.

21557356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34488 (or 34486 counting only the distinct ones).

The product of its digits is 31500, while the sum is 34.

The square root of 21557356 is about 4642.9899849127. The cubic root of 21557356 is about 278.3119352795.

The spelling of 21557356 in words is "twenty-one million, five hundred fifty-seven thousand, three hundred fifty-six".