31278013 has 6 divisors (see below), whose sum is σ = 33869274. Its totient is φ = 28871856.

The previous prime is 31278001. The next prime is 31278017. The reversal of 31278013 is 31087213.

It can be written as a sum of positive squares in 3 ways, for example, as 1006009 + 30272004 = 1003^2 + 5502^2 .

It is a de Polignac number, because none of the positive numbers 2^k-31278013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31278017) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 92370 + ... + 92707.

It is an arithmetic number, because the mean of its divisors is an integer number (5644879).

Almost surely, 2^31278013 is an apocalyptic number.

It is an amenable number.

31278013 is a deficient number, since it is larger than the sum of its proper divisors (2591261).

31278013 is a wasteful number, since it uses less digits than its factorization.

31278013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185103 (or 185090 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 31278013 is about 5592.6749413854. The cubic root of 31278013 is about 315.0743521471.

The spelling of 31278013 in words is "thirty-one million, two hundred seventy-eight thousand, thirteen".