21716556 has 24 divisors (see below), whose sum is σ = 50809584. Its totient is φ = 7219200.

The previous prime is 21716533. The next prime is 21716567. The reversal of 21716556 is 65561712.

It is a super-2 number, since 2×21716556² = 943217609002272, which contains 22 as substring.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2556 + ... + 7068.

It is an arithmetic number, because the mean of its divisors is an integer number (2117066).

Almost surely, 2^21716556 is an apocalyptic number.

It is an amenable number.

21716556 is an abundant number, since it is smaller than the sum of its proper divisors (29093028).

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

21716556 is a wasteful number, since it uses less digits than its factorization.

21716556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4921 (or 4919 counting only the distinct ones).

The product of its digits is 12600, while the sum is 33.

The square root of 21716556 is about 4660.1025739784. The cubic root of 21716556 is about 278.9953622641.

The spelling of 21716556 in words is "twenty-one million, seven hundred sixteen thousand, five hundred fifty-six".