31240121221 has 4 divisors (see below), whose sum is σ = 31966635712. Its totient is φ = 30513606732.

The previous prime is 31240121201. The next prime is 31240121251. The reversal of 31240121221 is 12212104213.

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 a de Polignac number, because none of the positive numbers 2^k-31240121221 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 (31240121201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363257181 + ... + 363257266.

It is an arithmetic number, because the mean of its divisors is an integer number (7991658928).

Almost surely, 2^31240121221 is an apocalyptic number.

It is an amenable number.

31240121221 is a deficient number, since it is larger than the sum of its proper divisors (726514491).

31240121221 is an equidigital number, since it uses as much as digits as its factorization.

31240121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726514490.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 31240121221 its reverse (12212104213), we get a palindrome (43452225434).

The spelling of 31240121221 in words is "thirty-one billion, two hundred forty million, one hundred twenty-one thousand, two hundred twenty-one".