21976881 has 4 divisors (see below), whose sum is σ = 29302512. Its totient is φ = 14651252.

The previous prime is 21976847. The next prime is 21976909. The reversal of 21976881 is 18867912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21976881 - 2⁶ = 21976817 is a prime.

It is a super-2 number, since 2×21976881² = 965966596976322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21976831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3662811 + ... + 3662816.

It is an arithmetic number, because the mean of its divisors is an integer number (7325628).

Almost surely, 2^21976881 is an apocalyptic number.

It is an amenable number.

21976881 is a deficient number, since it is larger than the sum of its proper divisors (7325631).

21976881 is an equidigital number, since it uses as much as digits as its factorization.

21976881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7325630.

The product of its digits is 48384, while the sum is 42.

The square root of 21976881 is about 4687.9506183406. The cubic root of 21976881 is about 280.1057466226.

The spelling of 21976881 in words is "twenty-one million, nine hundred seventy-six thousand, eight hundred eighty-one".