21123331331 has 2 divisors, whose sum is σ = 21123331332. Its totient is φ = 21123331330.

The previous prime is 21123331291. The next prime is 21123331337. The reversal of 21123331331 is 13313332112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123331331 is a prime.

It is a super-2 number, since 2×21123331331² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21123331297 and 21123331306.

It is not a weakly prime, because it can be changed into another prime (21123331337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561665665 + 10561665666.

It is an arithmetic number, because the mean of its divisors is an integer number (10561665666).

Almost surely, 2^21123331331 is an apocalyptic number.

21123331331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123331331 is an equidigital number, since it uses as much as digits as its factorization.

21123331331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 972, while the sum is 23.

Adding to 21123331331 its reverse (13313332112), we get a palindrome (34436663443).

The spelling of 21123331331 in words is "twenty-one billion, one hundred twenty-three million, three hundred thirty-one thousand, three hundred thirty-one".