31641991 has 4 divisors (see below), whose sum is σ = 31831632. Its totient is φ = 31452352.

The previous prime is 31641971. The next prime is 31642003. The reversal of 31641991 is 19914613.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19914613 = 2971 ⋅6703.

It is a cyclic number.

It is not a de Polignac number, because 31641991 - 2⁵ = 31641959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31641971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94570 + ... + 94903.

It is an arithmetic number, because the mean of its divisors is an integer number (7957908).

Almost surely, 2^31641991 is an apocalyptic number.

31641991 is a deficient number, since it is larger than the sum of its proper divisors (189641).

31641991 is a wasteful number, since it uses less digits than its factorization.

31641991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189640.

The product of its digits is 5832, while the sum is 34.

The square root of 31641991 is about 5625.1214209117. The cubic root of 31641991 is about 316.2918010435.

The spelling of 31641991 in words is "thirty-one million, six hundred forty-one thousand, nine hundred ninety-one".