21713709939 has 4 divisors (see below), whose sum is σ = 28951613256. Its totient is φ = 14475806624.

The previous prime is 21713709931. The next prime is 21713709947. The reversal of 21713709939 is 93990731712.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (21713709931) and next prime (21713709947).

It is a cyclic number.

It is not a de Polignac number, because 21713709939 - 2³ = 21713709931 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21713709891 and 21713709900.

It is not an unprimeable number, because it can be changed into a prime (21713709931) 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, 3618951654 + ... + 3618951659.

It is an arithmetic number, because the mean of its divisors is an integer number (7237903314).

Almost surely, 2^21713709939 is an apocalyptic number.

21713709939 is a deficient number, since it is larger than the sum of its proper divisors (7237903317).

21713709939 is an equidigital number, since it uses as much as digits as its factorization.

21713709939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7237903316.

The product of its (nonzero) digits is 642978, while the sum is 51.

The spelling of 21713709939 in words is "twenty-one billion, seven hundred thirteen million, seven hundred nine thousand, nine hundred thirty-nine".