31536661 has 4 divisors (see below), whose sum is σ = 33962572. Its totient is φ = 29110752.

The previous prime is 31536629. The next prime is 31536697. The reversal of 31536661 is 16663513.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16663513 = 19 ⋅877027.

It can be written as a sum of positive squares in 2 ways, for example, as 20520900 + 11015761 = 4530^2 + 3319^2 .

It is a cyclic number.

It is not a de Polignac number, because 31536661 - 2⁵ = 31536629 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 (31536061) 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, 1212936 + ... + 1212961.

It is an arithmetic number, because the mean of its divisors is an integer number (8490643).

Almost surely, 2^31536661 is an apocalyptic number.

It is an amenable number.

31536661 is a deficient number, since it is larger than the sum of its proper divisors (2425911).

31536661 is a wasteful number, since it uses less digits than its factorization.

31536661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2425910.

The product of its digits is 9720, while the sum is 31.

The square root of 31536661 is about 5615.7511518941. The cubic root of 31536661 is about 315.9404530482.

The spelling of 31536661 in words is "thirty-one million, five hundred thirty-six thousand, six hundred sixty-one".