13939799921 has 4 divisors (see below), whose sum is σ = 14077817844. Its totient is φ = 13801782000.

The previous prime is 13939799903. The next prime is 13939799933. The reversal of 13939799921 is 12999793931.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6587594896 + 7352205025 = 81164^2 + 85745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13939799921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13939799021) 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, 69008810 + ... + 69009011.

It is an arithmetic number, because the mean of its divisors is an integer number (3519454461).

Almost surely, 2^13939799921 is an apocalyptic number.

It is an amenable number.

13939799921 is a deficient number, since it is larger than the sum of its proper divisors (138017923).

13939799921 is a wasteful number, since it uses less digits than its factorization.

13939799921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138017922.

The product of its digits is 7440174, while the sum is 62.

The spelling of 13939799921 in words is "thirteen billion, nine hundred thirty-nine million, seven hundred ninety-nine thousand, nine hundred twenty-one".