21157637633 has 4 divisors (see below), whose sum is σ = 23081059248. Its totient is φ = 19234216020.

The previous prime is 21157637621. The next prime is 21157637639. The reversal of 21157637633 is 33673675112.

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 21157637633 - 2¹⁰ = 21157636609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21157637639) 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, 961710791 + ... + 961710812.

It is an arithmetic number, because the mean of its divisors is an integer number (5770264812).

Almost surely, 2^21157637633 is an apocalyptic number.

It is an amenable number.

21157637633 is a deficient number, since it is larger than the sum of its proper divisors (1923421615).

21157637633 is a wasteful number, since it uses less digits than its factorization.

21157637633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923421614.

The product of its digits is 476280, while the sum is 44.

The spelling of 21157637633 in words is "twenty-one billion, one hundred fifty-seven million, six hundred thirty-seven thousand, six hundred thirty-three".