31520389 has 2 divisors, whose sum is σ = 31520390. Its totient is φ = 31520388.

The previous prime is 31520387. The next prime is 31520393. The reversal of 31520389 is 98302513.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 10452289 = 4590^2 + 3233^2 .

It is an emirp because it is prime and its reverse (98302513) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31520389 - 2¹ = 31520387 is a prime.

It is a super-2 number, since 2×31520389² = 1987069845422642, which contains 22 as substring.

Together with 31520387, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 31520389.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31520387) 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, 15760194 + 15760195.

It is an arithmetic number, because the mean of its divisors is an integer number (15760195).

Almost surely, 2^31520389 is an apocalyptic number.

It is an amenable number.

31520389 is a deficient number, since it is larger than the sum of its proper divisors (1).

31520389 is an equidigital number, since it uses as much as digits as its factorization.

31520389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 31520389 is about 5614.3021828184. The cubic root of 31520389 is about 315.8861050044.

The spelling of 31520389 in words is "thirty-one million, five hundred twenty thousand, three hundred eighty-nine".