31023121021 has 2 divisors, whose sum is σ = 31023121022. Its totient is φ = 31023121020.

The previous prime is 31023120991. The next prime is 31023121037. The reversal of 31023121021 is 12012132013.

It is an a-pointer prime, because the next prime (31023121037) can be obtained adding 31023121021 to its sum of digits (16).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28633377796 + 2389743225 = 169214^2 + 48885^2 .

It is a cyclic number.

It is not a de Polignac number, because 31023121021 - 2⁷ = 31023120893 is a prime.

It is a super-2 number, since 2×31023121021² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 31023120986 and 31023121004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31023128021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15511560510 + 15511560511.

It is an arithmetic number, because the mean of its divisors is an integer number (15511560511).

Almost surely, 2^31023121021 is an apocalyptic number.

It is an amenable number.

31023121021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31023121021 is an equidigital number, since it uses as much as digits as its factorization.

31023121021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 31023121021 its reverse (12012132013), we get a palindrome (43035253034).

The spelling of 31023121021 in words is "thirty-one billion, twenty-three million, one hundred twenty-one thousand, twenty-one".