21984957 has 24 divisors (see below), whose sum is σ = 33852000. Its totient is φ = 13709088.

The previous prime is 21984947. The next prime is 21984967. The reversal of 21984957 is 75948912.

It is an interprime number because it is at equal distance from previous prime (21984947) and next prime (21984967).

It is not a de Polignac number, because 21984957 - 2⁷ = 21984829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21984917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13419 + ... + 14967.

It is an arithmetic number, because the mean of its divisors is an integer number (1410500).

Almost surely, 2^21984957 is an apocalyptic number.

It is an amenable number.

21984957 is a deficient number, since it is larger than the sum of its proper divisors (11867043).

21984957 is a wasteful number, since it uses less digits than its factorization.

21984957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1657 (or 1654 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 21984957 is about 4688.8118964190. The cubic root of 21984957 is about 280.1400532344.

The spelling of 21984957 in words is "twenty-one million, nine hundred eighty-four thousand, nine hundred fifty-seven".