31897728719 has 4 divisors (see below), whose sum is σ = 31909736544. Its totient is φ = 31885720896.

The previous prime is 31897728689. The next prime is 31897728743. The reversal of 31897728719 is 91782779813.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31897728719 - 2⁸ = 31897728463 is a prime.

It is a super-2 number, since 2×31897728719² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31897728019) 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, 5999927 + ... + 6005240.

It is an arithmetic number, because the mean of its divisors is an integer number (7977434136).

Almost surely, 2^31897728719 is an apocalyptic number.

31897728719 is a deficient number, since it is larger than the sum of its proper divisors (12007825).

31897728719 is a wasteful number, since it uses less digits than its factorization.

31897728719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12007824.

The product of its digits is 10668672, while the sum is 62.

The spelling of 31897728719 in words is "thirty-one billion, eight hundred ninety-seven million, seven hundred twenty-eight thousand, seven hundred nineteen".