538638623521 has 16 divisors (see below), whose sum is σ = 573398873424. Its totient is φ = 504221220864.

The previous prime is 538638623447. The next prime is 538638623533. The reversal of 538638623521 is 125326836835.

It can be written as a sum of positive squares in 8 ways, for example, as 9366368400 + 529272255121 = 96780^2 + 727511^2 .

It is a cyclic number.

It is not a de Polignac number, because 538638623521 - 2²⁵ = 538605069089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (538638626521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18664315 + ... + 18693151.

It is an arithmetic number, because the mean of its divisors is an integer number (35837429589).

Almost surely, 2^538638623521 is an apocalyptic number.

It is an amenable number.

538638623521 is a deficient number, since it is larger than the sum of its proper divisors (34760249903).

538638623521 is a wasteful number, since it uses less digits than its factorization.

538638623521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34740.

The product of its digits is 6220800, while the sum is 52.

The spelling of 538638623521 in words is "five hundred thirty-eight billion, six hundred thirty-eight million, six hundred twenty-three thousand, five hundred twenty-one".