21305038568138 has 8 divisors (see below), whose sum is σ = 34415831533188. Its totient is φ = 9833094723744.

The previous prime is 21305038568111. The next prime is 21305038568173. The reversal of 21305038568138 is 83186583050312.

It can be written as a sum of positive squares in 2 ways, for example, as 20983847740969 + 321190827169 = 4580813^2 + 566737^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21305038568138.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 409712280131 + ... + 409712280182.

Almost surely, 2^{21305038568138} is an apocalyptic number.

21305038568138 is a deficient number, since it is larger than the sum of its proper divisors (13110792965050).

21305038568138 is a wasteful number, since it uses less digits than its factorization.

21305038568138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819424560328.

The product of its (nonzero) digits is 4147200, while the sum is 53.

The spelling of 21305038568138 in words is "twenty-one trillion, three hundred five billion, thirty-eight million, five hundred sixty-eight thousand, one hundred thirty-eight".