31321220213021 has 4 divisors (see below), whose sum is σ = 33163644931452. Its totient is φ = 29478795494592.

The previous prime is 31321220213009. The next prime is 31321220213033. The reversal of 31321220213021 is 12031202212313.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (31321220213009) and next prime (31321220213033).

It can be written as a sum of positive squares in 2 ways, for example, as 28089894000100 + 3231326212921 = 5299990^2 + 1797589^2 .

It is a cyclic number.

It is not a de Polignac number, because 31321220213021 - 2³⁰ = 31320146471197 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 (31321220213051) 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, 921212359190 + ... + 921212359223.

It is an arithmetic number, because the mean of its divisors is an integer number (8290911232863).

Almost surely, 2^{31321220213021} is an apocalyptic number.

It is an amenable number.

31321220213021 is a deficient number, since it is larger than the sum of its proper divisors (1842424718431).

31321220213021 is a wasteful number, since it uses less digits than its factorization.

31321220213021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1842424718430.

The product of its (nonzero) digits is 864, while the sum is 23.

Adding to 31321220213021 its reverse (12031202212313), we get a palindrome (43352422425334).

The spelling of 31321220213021 in words is "thirty-one trillion, three hundred twenty-one billion, two hundred twenty million, two hundred thirteen thousand, twenty-one".