30721665609 has 16 divisors (see below), whose sum is σ = 45519154240. Its totient is φ = 20478601440.

The previous prime is 30721665581. The next prime is 30721665629. The reversal of 30721665609 is 90656612703.

30721665609 is a `hidden beast` number, since 3 + 0 + 7 + 21 + 66 + 560 + 9 = 666.

It is not a de Polignac number, because 30721665609 - 2²⁵ = 30688111177 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (30721665629) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 169749 + ... + 300429.

It is an arithmetic number, because the mean of its divisors is an integer number (2844947140).

Almost surely, 2^30721665609 is an apocalyptic number.

It is an amenable number.

30721665609 is a deficient number, since it is larger than the sum of its proper divisors (14797488631).

30721665609 is a wasteful number, since it uses less digits than its factorization.

30721665609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139397 (or 139391 counting only the distinct ones).

The product of its (nonzero) digits is 408240, while the sum is 45.

The spelling of 30721665609 in words is "thirty billion, seven hundred twenty-one million, six hundred sixty-five thousand, six hundred nine".