31713821 has 2 divisors, whose sum is σ = 31713822. Its totient is φ = 31713820.

The previous prime is 31713817. The next prime is 31713827. The reversal of 31713821 is 12831713.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29920900 + 1792921 = 5470^2 + 1339^2 .

It is a cyclic number.

It is not a de Polignac number, because 31713821 - 2² = 31713817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31713827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15856910 + 15856911.

It is an arithmetic number, because the mean of its divisors is an integer number (15856911).

Almost surely, 2^31713821 is an apocalyptic number.

It is an amenable number.

31713821 is a deficient number, since it is larger than the sum of its proper divisors (1).

31713821 is an equidigital number, since it uses as much as digits as its factorization.

31713821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 26.

The square root of 31713821 is about 5631.5025526053. The cubic root of 31713821 is about 316.5309565608.

The spelling of 31713821 in words is "thirty-one million, seven hundred thirteen thousand, eight hundred twenty-one".