31891973 has 8 divisors (see below), whose sum is σ = 32754456. Its totient is φ = 31033600.

The previous prime is 31891943. The next prime is 31891997. The reversal of 31891973 is 37919813.

It can be written as a sum of positive squares in 4 ways, for example, as 1399489 + 30492484 = 1183^2 + 5522^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31891973 - 2¹⁴ = 31875589 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31891973.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31891913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20615 + ... + 22107.

It is an arithmetic number, because the mean of its divisors is an integer number (4094307).

Almost surely, 2^31891973 is an apocalyptic number.

It is an amenable number.

31891973 is a deficient number, since it is larger than the sum of its proper divisors (862483).

31891973 is a wasteful number, since it uses less digits than its factorization.

31891973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2055.

The product of its digits is 40824, while the sum is 41.

The square root of 31891973 is about 5647.2978494144. The cubic root of 31891973 is about 317.1225530982.

The spelling of 31891973 in words is "thirty-one million, eight hundred ninety-one thousand, nine hundred seventy-three".