31491973 has 4 divisors (see below), whose sum is σ = 33344460. Its totient is φ = 29639488.

The previous prime is 31491959. The next prime is 31491983. The reversal of 31491973 is 37919413.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11573604 + 19918369 = 3402^2 + 4463^2 .

It is a cyclic number.

It is not a de Polignac number, because 31491973 - 2⁹ = 31491461 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 (31491913) 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 3 ways as a sum of consecutive naturals, for example, 926218 + ... + 926251.

It is an arithmetic number, because the mean of its divisors is an integer number (8336115).

Almost surely, 2^31491973 is an apocalyptic number.

It is an amenable number.

31491973 is a deficient number, since it is larger than the sum of its proper divisors (1852487).

31491973 is a wasteful number, since it uses less digits than its factorization.

31491973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1852486.

The product of its digits is 20412, while the sum is 37.

The square root of 31491973 is about 5611.7709326023. The cubic root of 31491973 is about 315.7911514565.

The spelling of 31491973 in words is "thirty-one million, four hundred ninety-one thousand, nine hundred seventy-three".