31987191 has 4 divisors (see below), whose sum is σ = 42649592. Its totient is φ = 21324792.

The previous prime is 31987147. The next prime is 31987211. The reversal of 31987191 is 19178913.

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

It is not a de Polignac number, because 31987191 - 2⁷ = 31987063 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 (31987091) 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, 5331196 + ... + 5331201.

It is an arithmetic number, because the mean of its divisors is an integer number (10662398).

Almost surely, 2^31987191 is an apocalyptic number.

31987191 is a deficient number, since it is larger than the sum of its proper divisors (10662401).

31987191 is a wasteful number, since it uses less digits than its factorization.

31987191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10662400.

The product of its digits is 13608, while the sum is 39.

The square root of 31987191 is about 5655.7219698284. The cubic root of 31987191 is about 317.4378442819.

The spelling of 31987191 in words is "thirty-one million, nine hundred eighty-seven thousand, one hundred ninety-one".