31691533 has 2 divisors, whose sum is σ = 31691534. Its totient is φ = 31691532.

The previous prime is 31691531. The next prime is 31691557. The reversal of 31691533 is 33519613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30614089 + 1077444 = 5533^2 + 1038^2 .

It is a cyclic number.

It is not a de Polignac number, because 31691533 - 2¹ = 31691531 is a prime.

Together with 31691531, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 31691495 and 31691504.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31691531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15845766 + 15845767.

It is an arithmetic number, because the mean of its divisors is an integer number (15845767).

Almost surely, 2^31691533 is an apocalyptic number.

It is an amenable number.

31691533 is a deficient number, since it is larger than the sum of its proper divisors (1).

31691533 is an equidigital number, since it uses as much as digits as its factorization.

31691533 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7290, while the sum is 31.

The square root of 31691533 is about 5629.5233368377. The cubic root of 31691533 is about 316.4567881062.

The spelling of 31691533 in words is "thirty-one million, six hundred ninety-one thousand, five hundred thirty-three".