21321213131 has 2 divisors, whose sum is σ = 21321213132. Its totient is φ = 21321213130.

The previous prime is 21321213127. The next prime is 21321213157. The reversal of 21321213131 is 13131212312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21321213131 - 2² = 21321213127 is a prime.

It is a super-2 number, since 2×21321213131² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21321213161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660606565 + 10660606566.

It is an arithmetic number, because the mean of its divisors is an integer number (10660606566).

Almost surely, 2^21321213131 is an apocalyptic number.

21321213131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321213131 is an equidigital number, since it uses as much as digits as its factorization.

21321213131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 20.

Adding to 21321213131 its reverse (13131212312), we get a palindrome (34452425443).

The spelling of 21321213131 in words is "twenty-one billion, three hundred twenty-one million, two hundred thirteen thousand, one hundred thirty-one".