31500121 has 4 divisors (see below), whose sum is σ = 31521744. Its totient is φ = 31478500.

The previous prime is 31500113. The next prime is 31500149. The reversal of 31500121 is 12100513.

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.

It is a cyclic number.

It is not a de Polignac number, because 31500121 - 2³ = 31500113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31500101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8455 + ... + 11596.

It is an arithmetic number, because the mean of its divisors is an integer number (7880436).

Almost surely, 2^31500121 is an apocalyptic number.

It is an amenable number.

31500121 is a deficient number, since it is larger than the sum of its proper divisors (21623).

31500121 is a wasteful number, since it uses less digits than its factorization.

31500121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21622.

The product of its (nonzero) digits is 30, while the sum is 13.

The square root of 31500121 is about 5612.4968596873. The cubic root of 31500121 is about 315.8183842630.

Adding to 31500121 its reverse (12100513), we get a palindrome (43600634).

The spelling of 31500121 in words is "thirty-one million, five hundred thousand, one hundred twenty-one".