31378720065 has 48 divisors (see below), whose sum is σ = 63068659584. Its totient is φ = 13040501760.

The previous prime is 31378720033. The next prime is 31378720141. The reversal of 31378720065 is 56002787313.

It is not a de Polignac number, because 31378720065 - 2⁵ = 31378720033 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 31378719999 and 31378720026.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1222192 + ... + 1247601.

It is an arithmetic number, because the mean of its divisors is an integer number (1313930408).

Almost surely, 2^31378720065 is an apocalyptic number.

31378720065 is a gapful number since it is divisible by the number (35) formed by its first and last digit.

It is an amenable number.

31378720065 is an abundant number, since it is smaller than the sum of its proper divisors (31689939519).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31378720065 is a wasteful number, since it uses less digits than its factorization.

31378720065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2469830 (or 2469819 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 42.

The spelling of 31378720065 in words is "thirty-one billion, three hundred seventy-eight million, seven hundred twenty thousand, sixty-five".