21572051767 has 4 divisors (see below), whose sum is σ = 24653773456. Its totient is φ = 18490330080.

The previous prime is 21572051759. The next prime is 21572051783. The reversal of 21572051767 is 76715027512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21572051767 - 2³ = 21572051759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21572051167) 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, 1540860834 + ... + 1540860847.

It is an arithmetic number, because the mean of its divisors is an integer number (6163443364).

Almost surely, 2^21572051767 is an apocalyptic number.

21572051767 is a deficient number, since it is larger than the sum of its proper divisors (3081721689).

21572051767 is an equidigital number, since it uses as much as digits as its factorization.

21572051767 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3081721688.

The product of its (nonzero) digits is 205800, while the sum is 43.

The spelling of 21572051767 in words is "twenty-one billion, five hundred seventy-two million, fifty-one thousand, seven hundred sixty-seven".