21131220413 has 2 divisors, whose sum is σ = 21131220414. Its totient is φ = 21131220412.

The previous prime is 21131220361. The next prime is 21131220419. The reversal of 21131220413 is 31402213112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13081183129 + 8050037284 = 114373^2 + 89722^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131220413 - 2⁸ = 21131220157 is a prime.

It is a super-2 number, since 2×21131220413² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131220419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565610206 + 10565610207.

It is an arithmetic number, because the mean of its divisors is an integer number (10565610207).

Almost surely, 2^21131220413 is an apocalyptic number.

It is an amenable number.

21131220413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131220413 is an equidigital number, since it uses as much as digits as its factorization.

21131220413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 21131220413 its reverse (31402213112), we get a palindrome (52533433525).

The spelling of 21131220413 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty thousand, four hundred thirteen".