31031220011021 has 4 divisors (see below), whose sum is σ = 31032228170844. Its totient is φ = 31030211851200.

The previous prime is 31031220010981. The next prime is 31031220011023. The reversal of 31031220011021 is 12011002213013.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18305690605225 + 12725529405796 = 4278515^2 + 3567286^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31031220011021 is a prime.

It is a super-2 number, since 2×31031220011021² (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 (31031220011023) 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, 504033740 + ... + 504095301.

It is an arithmetic number, because the mean of its divisors is an integer number (7758057042711).

Almost surely, 2^{31031220011021} is an apocalyptic number.

It is an amenable number.

31031220011021 is a deficient number, since it is larger than the sum of its proper divisors (1008159823).

31031220011021 is a wasteful number, since it uses less digits than its factorization.

31031220011021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1008159822.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 31031220011021 its reverse (12011002213013), we get a palindrome (43042222224034).

The spelling of 31031220011021 in words is "thirty-one trillion, thirty-one billion, two hundred twenty million, eleven thousand, twenty-one".