20100131021 has 2 divisors, whose sum is σ = 20100131022. Its totient is φ = 20100131020.

The previous prime is 20100131017. The next prime is 20100131071. The reversal of 20100131021 is 12013100102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15413222500 + 4686908521 = 124150^2 + 68461^2 .

It is a cyclic number.

It is not a de Polignac number, because 20100131021 - 2² = 20100131017 is a prime.

It is a super-2 number, since 2×20100131021² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20100130993 and 20100131011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20100131071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10050065510 + 10050065511.

It is an arithmetic number, because the mean of its divisors is an integer number (10050065511).

Almost surely, 2^20100131021 is an apocalyptic number.

It is an amenable number.

20100131021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20100131021 is an equidigital number, since it uses as much as digits as its factorization.

20100131021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 11.

Adding to 20100131021 its reverse (12013100102), we get a palindrome (32113231123).

The spelling of 20100131021 in words is "twenty billion, one hundred million, one hundred thirty-one thousand, twenty-one".