21981976 has 32 divisors (see below), whose sum is σ = 42900480. Its totient is φ = 10548000.

The previous prime is 21981961. The next prime is 21981977. The reversal of 21981976 is 67918912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981977) by changing a digit.

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, 37155 + ... + 37741.

It is an arithmetic number, because the mean of its divisors is an integer number (1340640).

Almost surely, 2^21981976 is an apocalyptic number.

It is an amenable number.

21981976 is a deficient number, since it is larger than the sum of its proper divisors (20918504).

21981976 is a wasteful number, since it uses less digits than its factorization.

21981976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775 (or 771 counting only the distinct ones).

The product of its digits is 54432, while the sum is 43.

The square root of 21981976 is about 4688.4940012759. The cubic root of 21981976 is about 280.1273910120.

The spelling of 21981976 in words is "twenty-one million, nine hundred eighty-one thousand, nine hundred seventy-six".