31936813 has 2 divisors, whose sum is σ = 31936814. Its totient is φ = 31936812.

The previous prime is 31936787. The next prime is 31936819. The reversal of 31936813 is 31863913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31787044 + 149769 = 5638^2 + 387^2 .

It is an emirp because it is prime and its reverse (31863913) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31936813 - 2¹³ = 31928621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31936819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15968406 + 15968407.

It is an arithmetic number, because the mean of its divisors is an integer number (15968407).

Almost surely, 2^31936813 is an apocalyptic number.

It is an amenable number.

31936813 is a deficient number, since it is larger than the sum of its proper divisors (1).

31936813 is an equidigital number, since it uses as much as digits as its factorization.

31936813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11664, while the sum is 34.

The square root of 31936813 is about 5651.2664952203. The cubic root of 31936813 is about 317.2711078893.

Subtracting from 31936813 its reverse (31863913), we obtain a square (72900 = 270²).

The spelling of 31936813 in words is "thirty-one million, nine hundred thirty-six thousand, eight hundred thirteen".