31513861 has 4 divisors (see below), whose sum is σ = 31534924. Its totient is φ = 31492800.

The previous prime is 31513849. The next prime is 31513873. The reversal of 31513861 is 16831513.

31513861 = 3969² + 3970².

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

It is an interprime number because it is at equal distance from previous prime (31513849) and next prime (31513873).

It can be written as a sum of positive squares in 2 ways, for example, as 15760900 + 15752961 = 3970^2 + 3969^2 .

It is a 3-Lehmer number, since φ(31513861) divides (31513861-1)³.

It is a cyclic number.

It is not a de Polignac number, because 31513861 - 2¹¹ = 31511813 is a prime.

It is a deceptive number, since it divides R_31513860.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31513831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8100 + ... + 11341.

It is an arithmetic number, because the mean of its divisors is an integer number (7883731).

Almost surely, 2^31513861 is an apocalyptic number.

31513861 is the 3970-th centered square number.

It is an amenable number.

31513861 is a deficient number, since it is larger than the sum of its proper divisors (21063).

31513861 is a wasteful number, since it uses less digits than its factorization.

31513861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21062.

The product of its digits is 2160, while the sum is 28.

The square root of 31513861 is about 5613.7207803737. The cubic root of 31513861 is about 315.8642964023.

The spelling of 31513861 in words is "thirty-one million, five hundred thirteen thousand, eight hundred sixty-one".