31281013 has 4 divisors (see below), whose sum is σ = 31590828. Its totient is φ = 30971200.

The previous prime is 31280987. The next prime is 31281017. The reversal of 31281013 is 31018213.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28976689 + 2304324 = 5383^2 + 1518^2 .

It is a cyclic number.

It is not a de Polignac number, because 31281013 - 2⁵ = 31280981 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 (31281017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154756 + ... + 154957.

It is an arithmetic number, because the mean of its divisors is an integer number (7897707).

Almost surely, 2^31281013 is an apocalyptic number.

It is an amenable number.

31281013 is a deficient number, since it is larger than the sum of its proper divisors (309815).

31281013 is a wasteful number, since it uses less digits than its factorization.

31281013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309814.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 31281013 is about 5592.9431429257. The cubic root of 31281013 is about 315.0844251745.

Adding to 31281013 its reverse (31018213), we get a palindrome (62299226).

The spelling of 31281013 in words is "thirty-one million, two hundred eighty-one thousand, thirteen".