31666397 has 6 divisors (see below), whose sum is σ = 36836478. Its totient is φ = 27142584.

The previous prime is 31666379. The next prime is 31666399. The reversal of 31666397 is 79366613.

It can be written as a sum of positive squares in only one way, i.e., 31595641 + 70756 = 5621^2 + 266^2 .

It is not a de Polignac number, because 31666397 - 2¹⁶ = 31600861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31666399) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 323078 + ... + 323175.

It is an arithmetic number, because the mean of its divisors is an integer number (6139413).

Almost surely, 2^31666397 is an apocalyptic number.

It is an amenable number.

31666397 is a deficient number, since it is larger than the sum of its proper divisors (5170081).

31666397 is an equidigital number, since it uses as much as digits as its factorization.

31666397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 646267 (or 646260 counting only the distinct ones).

The product of its digits is 122472, while the sum is 41.

The square root of 31666397 is about 5627.2903781483. The cubic root of 31666397 is about 316.3731005403.

The spelling of 31666397 in words is "thirty-one million, six hundred sixty-six thousand, three hundred ninety-seven".