636692542021 has 4 divisors (see below), whose sum is σ = 637999919392. Its totient is φ = 635385164652.

The previous prime is 636692541967. The next prime is 636692542033. The reversal of 636692542021 is 120245296636.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 636692542021 - 2³⁹ = 86936728133 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 (636192542021) 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 3 ways as a sum of consecutive naturals, for example, 653687955 + ... + 653688928.

It is an arithmetic number, because the mean of its divisors is an integer number (159499979848).

Almost surely, 2^636692542021 is an apocalyptic number.

It is an amenable number.

636692542021 is a deficient number, since it is larger than the sum of its proper divisors (1307377371).

636692542021 is a wasteful number, since it uses less digits than its factorization.

636692542021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1307377370.

The product of its (nonzero) digits is 933120, while the sum is 46.

The spelling of 636692542021 in words is "six hundred thirty-six billion, six hundred ninety-two million, five hundred forty-two thousand, twenty-one".