20531103431021 has 2 divisors, whose sum is σ = 20531103431022. Its totient is φ = 20531103431020.

The previous prime is 20531103431011. The next prime is 20531103431023. The reversal of 20531103431021 is 12013430113502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19006644034921 + 1524459396100 = 4359661^2 + 1234690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20531103431021 is a prime.

Together with 20531103431023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20531103431023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10265551715510 + 10265551715511.

It is an arithmetic number, because the mean of its divisors is an integer number (10265551715511).

Almost surely, 2^{20531103431021} is an apocalyptic number.

It is an amenable number.

20531103431021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20531103431021 is an equidigital number, since it uses as much as digits as its factorization.

20531103431021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

Adding to 20531103431021 its reverse (12013430113502), we get a palindrome (32544533544523).

The spelling of 20531103431021 in words is "twenty trillion, five hundred thirty-one billion, one hundred three million, four hundred thirty-one thousand, twenty-one".