31486721 has 16 divisors (see below), whose sum is σ = 37593600. Its totient is φ = 25800768.

The previous prime is 31486711. The next prime is 31486723. The reversal of 31486721 is 12768413.

It is not a de Polignac number, because 31486721 - 2⁶ = 31486657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31486723) 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, 21416 + ... + 22838.

It is an arithmetic number, because the mean of its divisors is an integer number (2349600).

Almost surely, 2^31486721 is an apocalyptic number.

It is an amenable number.

31486721 is a deficient number, since it is larger than the sum of its proper divisors (6106879).

31486721 is a wasteful number, since it uses less digits than its factorization.

31486721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1568.

The product of its digits is 8064, while the sum is 32.

The square root of 31486721 is about 5611.3029681171. The cubic root of 31486721 is about 315.7735953707.

The spelling of 31486721 in words is "thirty-one million, four hundred eighty-six thousand, seven hundred twenty-one".