31991685728709 has 16 divisors (see below), whose sum is σ = 48842446188032. Its totient is φ = 18246009226608.

The previous prime is 31991685728701. The next prime is 31991685728711. The reversal of 31991685728709 is 90782758619913.

It is not a de Polignac number, because 31991685728709 - 2³ = 31991685728701 is a prime.

It is a super-3 number, since 3×31991685728709³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31991685728701) 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, 1456407379 + ... + 1456429344.

It is an arithmetic number, because the mean of its divisors is an integer number (3052652886752).

Almost surely, 2^{31991685728709} is an apocalyptic number.

It is an amenable number.

31991685728709 is a deficient number, since it is larger than the sum of its proper divisors (16850760459323).

31991685728709 is a wasteful number, since it uses less digits than its factorization.

31991685728709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2912837256.

The product of its (nonzero) digits is 411505920, while the sum is 75.

The spelling of 31991685728709 in words is "thirty-one trillion, nine hundred ninety-one billion, six hundred eighty-five million, seven hundred twenty-eight thousand, seven hundred nine".