39685117921 has 4 divisors (see below), whose sum is σ = 40070410432. Its totient is φ = 39299825412.

The previous prime is 39685117891. The next prime is 39685117963. The reversal of 39685117921 is 12971158693.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 39685117921 - 2⁷ = 39685117793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39685117621) 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, 192646101 + ... + 192646306.

It is an arithmetic number, because the mean of its divisors is an integer number (10017602608).

Almost surely, 2^39685117921 is an apocalyptic number.

It is an amenable number.

39685117921 is a deficient number, since it is larger than the sum of its proper divisors (385292511).

39685117921 is a wasteful number, since it uses less digits than its factorization.

39685117921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385292510.

The product of its digits is 816480, while the sum is 52.

The spelling of 39685117921 in words is "thirty-nine billion, six hundred eighty-five million, one hundred seventeen thousand, nine hundred twenty-one".