21139647793 has 6 divisors (see below), whose sum is σ = 23236141922. Its totient is φ = 19217861520.

The previous prime is 21139647791. The next prime is 21139647799. The reversal of 21139647793 is 39774693112.

It can be written as a sum of positive squares in only one way, i.e., 16470385569 + 4669262224 = 128337^2 + 68332^2 .

It is not a de Polignac number, because 21139647793 - 2¹ = 21139647791 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21139647793.

It is not an unprimeable number, because it can be changed into a prime (21139647791) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87353796 + ... + 87354037.

Almost surely, 2^21139647793 is an apocalyptic number.

It is an amenable number.

21139647793 is a deficient number, since it is larger than the sum of its proper divisors (2096494129).

21139647793 is a wasteful number, since it uses less digits than its factorization.

21139647793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174707855 (or 174707844 counting only the distinct ones).

The product of its digits is 1714608, while the sum is 52.

The spelling of 21139647793 in words is "twenty-one billion, one hundred thirty-nine million, six hundred forty-seven thousand, seven hundred ninety-three".