31651661 has 4 divisors (see below), whose sum is σ = 31736892. Its totient is φ = 31566432.

The previous prime is 31651643. The next prime is 31651681. The reversal of 31651661 is 16615613.

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 13213225 + 18438436 = 3635^2 + 4294^2 .

It is a cyclic number.

It is not a de Polignac number, because 31651661 - 2⁶ = 31651597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31651621) 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, 42056 + ... + 42801.

It is an arithmetic number, because the mean of its divisors is an integer number (7934223).

Almost surely, 2^31651661 is an apocalyptic number.

It is an amenable number.

31651661 is a deficient number, since it is larger than the sum of its proper divisors (85231).

31651661 is an equidigital number, since it uses as much as digits as its factorization.

31651661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85230.

The product of its digits is 3240, while the sum is 29.

The square root of 31651661 is about 5625.9808922534. The cubic root of 31651661 is about 316.3240180448.

The spelling of 31651661 in words is "thirty-one million, six hundred fifty-one thousand, six hundred sixty-one".