31521667121 has 24 divisors (see below), whose sum is σ = 39042090720. Its totient is φ = 25287061632.

The previous prime is 31521667061. The next prime is 31521667129. The reversal of 31521667121 is 12176612513.

It is a happy number.

It is not a de Polignac number, because 31521667121 - 2¹⁰ = 31521666097 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (31521667129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43406 + ... + 254808.

It is an arithmetic number, because the mean of its divisors is an integer number (1626753780).

Almost surely, 2^31521667121 is an apocalyptic number.

It is an amenable number.

31521667121 is a deficient number, since it is larger than the sum of its proper divisors (7520423599).

31521667121 is a wasteful number, since it uses less digits than its factorization.

31521667121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211613 (or 211606 counting only the distinct ones).

The product of its digits is 15120, while the sum is 35.

The spelling of 31521667121 in words is "thirty-one billion, five hundred twenty-one million, six hundred sixty-seven thousand, one hundred twenty-one".