31990861 has 8 divisors (see below), whose sum is σ = 38150784. Its totient is φ = 26228400.

The previous prime is 31990831. The next prime is 31990897. The reversal of 31990861 is 16809913.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31990861 - 2⁹ = 31990349 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31990861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31990811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99190 + ... + 99511.

It is an arithmetic number, because the mean of its divisors is an integer number (4768848).

Almost surely, 2^31990861 is an apocalyptic number.

It is an amenable number.

31990861 is a deficient number, since it is larger than the sum of its proper divisors (6159923).

31990861 is a wasteful number, since it uses less digits than its factorization.

31990861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198731.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 31990861 is about 5656.0464107007. The cubic root of 31990861 is about 317.4499840614.

The spelling of 31990861 in words is "thirty-one million, nine hundred ninety thousand, eight hundred sixty-one".