31500397 has 4 divisors (see below), whose sum is σ = 31527580. Its totient is φ = 31473216.

The previous prime is 31500383. The next prime is 31500407. The reversal of 31500397 is 79300513.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79300513 = 89 ⋅891017.

It can be written as a sum of positive squares in 2 ways, for example, as 2920681 + 28579716 = 1709^2 + 5346^2 .

It is a cyclic number.

It is not a de Polignac number, because 31500397 - 2¹¹ = 31498349 is a prime.

It is a super-2 number, since 2×31500397² = 1984550022315218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31500367) 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, 11772 + ... + 14197.

It is an arithmetic number, because the mean of its divisors is an integer number (7881895).

Almost surely, 2^31500397 is an apocalyptic number.

It is an amenable number.

31500397 is a deficient number, since it is larger than the sum of its proper divisors (27183).

31500397 is a wasteful number, since it uses less digits than its factorization.

31500397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27182.

The product of its (nonzero) digits is 2835, while the sum is 28.

The square root of 31500397 is about 5612.5214476205. The cubic root of 31500397 is about 315.8193066470.

The spelling of 31500397 in words is "thirty-one million, five hundred thousand, three hundred ninety-seven".