31686409 has 4 divisors (see below), whose sum is σ = 31977220. Its totient is φ = 31395600.

The previous prime is 31686367. The next prime is 31686437. The reversal of 31686409 is 90468613.

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 25030009 + 6656400 = 5003^2 + 2580^2 .

It is a cyclic number.

It is not a de Polignac number, because 31686409 - 2¹³ = 31678217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31686469) 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, 145242 + ... + 145459.

It is an arithmetic number, because the mean of its divisors is an integer number (7994305).

Almost surely, 2^31686409 is an apocalyptic number.

It is an amenable number.

31686409 is a deficient number, since it is larger than the sum of its proper divisors (290811).

31686409 is a wasteful number, since it uses less digits than its factorization.

31686409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290810.

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 31686409 is about 5629.0682177426. The cubic root of 31686409 is about 316.4397318998.

The spelling of 31686409 in words is "thirty-one million, six hundred eighty-six thousand, four hundred nine".