31991007 has 16 divisors (see below), whose sum is σ = 43274592. Its totient is φ = 21020160.

The previous prime is 31990997. The next prime is 31991053. The reversal of 31991007 is 70019913.

It is not a de Polignac number, because 31991007 - 2⁶ = 31990943 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31991087) 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, 113707 + ... + 113987.

It is an arithmetic number, because the mean of its divisors is an integer number (2704662).

Almost surely, 2^31991007 is an apocalyptic number.

31991007 is a deficient number, since it is larger than the sum of its proper divisors (11283585).

31991007 is a wasteful number, since it uses less digits than its factorization.

31991007 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698.

The product of its (nonzero) digits is 1701, while the sum is 30.

The square root of 31991007 is about 5656.0593172279. The cubic root of 31991007 is about 317.4504669871.

It can be divided in two parts, 3 and 1991007, that added together give a triangular number (1991010 = T₁₉₉₅).

The spelling of 31991007 in words is "thirty-one million, nine hundred ninety-one thousand, seven".