31720741817221 has 4 divisors (see below), whose sum is σ = 31729807480000. Its totient is φ = 31711676154444.

The previous prime is 31720741817213. The next prime is 31720741817257. The reversal of 31720741817221 is 12271814702713.

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 31720741817221 - 2³ = 31720741817213 is a prime.

It is a super-2 number, since 2×31720741817221² (a number of 28 digits) 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 (31720741817201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4532826141 + ... + 4532833138.

It is an arithmetic number, because the mean of its divisors is an integer number (7932451870000).

Almost surely, 2^{31720741817221} is an apocalyptic number.

It is an amenable number.

31720741817221 is a deficient number, since it is larger than the sum of its proper divisors (9065662779).

31720741817221 is an equidigital number, since it uses as much as digits as its factorization.

31720741817221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9065662778.

The product of its (nonzero) digits is 263424, while the sum is 46.

The spelling of 31720741817221 in words is "thirty-one trillion, seven hundred twenty billion, seven hundred forty-one million, eight hundred seventeen thousand, two hundred twenty-one".