31980191 has 4 divisors (see below), whose sum is σ = 32018112. Its totient is φ = 31942272.

The previous prime is 31980187. The next prime is 31980199. The reversal of 31980191 is 19108913.

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 31980191 - 2² = 31980187 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 (31980199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17666 + ... + 19391.

It is an arithmetic number, because the mean of its divisors is an integer number (8004528).

Almost surely, 2^31980191 is an apocalyptic number.

31980191 is a deficient number, since it is larger than the sum of its proper divisors (37921).

31980191 is an equidigital number, since it uses as much as digits as its factorization.

31980191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37920.

The product of its (nonzero) digits is 1944, while the sum is 32.

The square root of 31980191 is about 5655.1030936668. The cubic root of 31980191 is about 317.4146868142.

The spelling of 31980191 in words is "thirty-one million, nine hundred eighty thousand, one hundred ninety-one".