31991123 has 4 divisors (see below), whose sum is σ = 32040768. Its totient is φ = 31941480.

The previous prime is 31991119. The next prime is 31991143. The reversal of 31991123 is 32119913.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32119913 = 7 ⋅4588559.

It is a cyclic number.

It is not a de Polignac number, because 31991123 - 2² = 31991119 is a prime.

It is a super-2 number, since 2×31991123² = 2046863901602258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31991143) 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, 23843 + ... + 25148.

It is an arithmetic number, because the mean of its divisors is an integer number (8010192).

Almost surely, 2^31991123 is an apocalyptic number.

31991123 is a deficient number, since it is larger than the sum of its proper divisors (49645).

31991123 is an equidigital number, since it uses as much as digits as its factorization.

31991123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49644.

The product of its digits is 1458, while the sum is 29.

The square root of 31991123 is about 5656.0695717079. The cubic root of 31991123 is about 317.4508506804.

The spelling of 31991123 in words is "thirty-one million, nine hundred ninety-one thousand, one hundred twenty-three".