21977856 has 54 divisors (see below), whose sum is σ = 63374220. Its totient is φ = 7325184.

The previous prime is 21977843. The next prime is 21977861. The reversal of 21977856 is 65877912.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 2466 + ... + 7073.

Almost surely, 2^21977856 is an apocalyptic number.

It is an amenable number.

21977856 is an abundant number, since it is smaller than the sum of its proper divisors (41396364).

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

21977856 is an equidigital number, since it uses as much as digits as its factorization.

21977856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9561 (or 9544 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 21977856 is about 4688.0546071905. The cubic root of 21977856 is about 280.1098888402.

The spelling of 21977856 in words is "twenty-one million, nine hundred seventy-seven thousand, eight hundred fifty-six".