31890561 has 16 divisors (see below), whose sum is σ = 43362816. Its totient is φ = 20843136.

The previous prime is 31890541. The next prime is 31890587. The reversal of 31890561 is 16509813.

It is not a de Polignac number, because 31890561 - 2⁹ = 31890049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31890511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48511 + ... + 49163.

It is an arithmetic number, because the mean of its divisors is an integer number (2710176).

Almost surely, 2^31890561 is an apocalyptic number.

It is an amenable number.

31890561 is a deficient number, since it is larger than the sum of its proper divisors (11472255).

31890561 is a wasteful number, since it uses less digits than its factorization.

31890561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952.

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 31890561 is about 5647.1728324888. The cubic root of 31890561 is about 317.1178728854.

The spelling of 31890561 in words is "thirty-one million, eight hundred ninety thousand, five hundred sixty-one".