31664397 has 4 divisors (see below), whose sum is σ = 42219200. Its totient is φ = 21109596.

The previous prime is 31664377. The next prime is 31664419. The reversal of 31664397 is 79346613.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 79346613 = 3 ⋅26448871.

It is not a de Polignac number, because 31664397 - 2¹² = 31660301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31664327) 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, 5277397 + ... + 5277402.

It is an arithmetic number, because the mean of its divisors is an integer number (10554800).

Almost surely, 2^31664397 is an apocalyptic number.

It is an amenable number.

31664397 is a deficient number, since it is larger than the sum of its proper divisors (10554803).

31664397 is a wasteful number, since it uses less digits than its factorization.

31664397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10554802.

The product of its digits is 81648, while the sum is 39.

The square root of 31664397 is about 5627.1126699223. The cubic root of 31664397 is about 316.3664398570.

It can be divided in two parts, 3 and 1664397, that added together give a triangular number (1664400 = T₁₈₂₄).

The spelling of 31664397 in words is "thirty-one million, six hundred sixty-four thousand, three hundred ninety-seven".