20643766451 has 32 divisors (see below), whose sum is σ = 27516423168. Its totient is φ = 14992727040.

The previous prime is 20643766447. The next prime is 20643766457. The reversal of 20643766451 is 15466734602.

It is not a de Polignac number, because 20643766451 - 2² = 20643766447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20643766457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 58271 + ... + 211383.

It is an arithmetic number, because the mean of its divisors is an integer number (859888224).

Almost surely, 2^20643766451 is an apocalyptic number.

20643766451 is a deficient number, since it is larger than the sum of its proper divisors (6872656717).

20643766451 is a wasteful number, since it uses less digits than its factorization.

20643766451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153251.

The product of its (nonzero) digits is 725760, while the sum is 44.

The spelling of 20643766451 in words is "twenty billion, six hundred forty-three million, seven hundred sixty-six thousand, four hundred fifty-one".