20643872 has 24 divisors (see below), whose sum is σ = 40896576. Its totient is φ = 10257472.

The previous prime is 20643851. The next prime is 20643893. The reversal of 20643872 is 27834602.

It is an interprime number because it is at equal distance from previous prime (20643851) and next prime (20643893).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3413 + ... + 7275.

It is an arithmetic number, because the mean of its divisors is an integer number (1704024).

Almost surely, 2^20643872 is an apocalyptic number.

It is an amenable number.

20643872 is a deficient number, since it is larger than the sum of its proper divisors (20252704).

20643872 is a wasteful number, since it uses less digits than its factorization.

20643872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4040 (or 4032 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 20643872 is about 4543.5527948952. The cubic root of 20643872 is about 274.3239459770.

The spelling of 20643872 in words is "twenty million, six hundred forty-three thousand, eight hundred seventy-two".