31388890655 has 4 divisors (see below), whose sum is σ = 37666668792. Its totient is φ = 25111112520.

The previous prime is 31388890651. The next prime is 31388890657. The reversal of 31388890655 is 55609888313.

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

It is not a de Polignac number, because 31388890655 - 2² = 31388890651 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31388890655.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31388890651) 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, 3138889061 + ... + 3138889070.

It is an arithmetic number, because the mean of its divisors is an integer number (9416667198).

Almost surely, 2^31388890655 is an apocalyptic number.

31388890655 is a deficient number, since it is larger than the sum of its proper divisors (6277778137).

31388890655 is an equidigital number, since it uses as much as digits as its factorization.

31388890655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6277778136.

The product of its (nonzero) digits is 6220800, while the sum is 56.

The spelling of 31388890655 in words is "thirty-one billion, three hundred eighty-eight million, eight hundred ninety thousand, six hundred fifty-five".