31500013 has 8 divisors (see below), whose sum is σ = 32462136. Its totient is φ = 30547200.

The previous prime is 31499989. The next prime is 31500017. The reversal of 31500013 is 31000513.

It can be written as a sum of positive squares in 4 ways, for example, as 2630884 + 28869129 = 1622^2 + 5373^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31500013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31499966 and 31500002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31500017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4873 + ... + 9313.

It is an arithmetic number, because the mean of its divisors is an integer number (4057767).

Almost surely, 2^31500013 is an apocalyptic number.

It is an amenable number.

31500013 is a deficient number, since it is larger than the sum of its proper divisors (962123).

31500013 is a wasteful number, since it uses less digits than its factorization.

31500013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4655.

The product of its (nonzero) digits is 45, while the sum is 13.

The square root of 31500013 is about 5612.4872382928. The cubic root of 31500013 is about 315.8180233287.

Adding to 31500013 its reverse (31000513), we get a palindrome (62500526).

Subtracting from 31500013 its reverse (31000513), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 31500013 in words is "thirty-one million, five hundred thousand, thirteen".