31720666 has 16 divisors (see below), whose sum is σ = 48295368. Its totient is φ = 15624000.

The previous prime is 31720651. The next prime is 31720669. The reversal of 31720666 is 66602713.

It can be written as a sum of positive squares in 4 ways, for example, as 26061025 + 5659641 = 5105^2 + 2379^2 .

It is not an unprimeable number, because it can be changed into a prime (31720669) 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, 75136 + ... + 75556.

Almost surely, 2^31720666 is an apocalyptic number.

31720666 is a deficient number, since it is larger than the sum of its proper divisors (16574702).

31720666 is a wasteful number, since it uses less digits than its factorization.

31720666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897.

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 31720666 is about 5632.1102617048. The cubic root of 31720666 is about 316.5537279001.

The spelling of 31720666 in words is "thirty-one million, seven hundred twenty thousand, six hundred sixty-six".