39666579921 has 6 divisors (see below), whose sum is σ = 57296171010. Its totient is φ = 26444386608.

The previous prime is 39666579917. The next prime is 39666579923. The reversal of 39666579921 is 12997566693.

It can be written as a sum of positive squares in only one way, i.e., 39247968321 + 418611600 = 198111^2 + 20460^2 .

It is not a de Polignac number, because 39666579921 - 2² = 39666579917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (39666579923) 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, 2203698876 + ... + 2203698893.

It is an arithmetic number, because the mean of its divisors is an integer number (9549361835).

Almost surely, 2^39666579921 is an apocalyptic number.

It is an amenable number.

39666579921 is a deficient number, since it is larger than the sum of its proper divisors (17629591089).

39666579921 is a wasteful number, since it uses less digits than its factorization.

39666579921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4407397775 (or 4407397772 counting only the distinct ones).

The product of its digits is 33067440, while the sum is 63.

The spelling of 39666579921 in words is "thirty-nine billion, six hundred sixty-six million, five hundred seventy-nine thousand, nine hundred twenty-one".