21123302831 has 2 divisors, whose sum is σ = 21123302832. Its totient is φ = 21123302830.

The previous prime is 21123302807. The next prime is 21123302867. The reversal of 21123302831 is 13820332112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21123302831 - 2²⁶ = 21056193967 is a prime.

It is a super-2 number, since 2×21123302831² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21123302831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123302881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561651415 + 10561651416.

It is an arithmetic number, because the mean of its divisors is an integer number (10561651416).

Almost surely, 2^21123302831 is an apocalyptic number.

21123302831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123302831 is an equidigital number, since it uses as much as digits as its factorization.

21123302831 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

Adding to 21123302831 its reverse (13820332112), we get a palindrome (34943634943).

The spelling of 21123302831 in words is "twenty-one billion, one hundred twenty-three million, three hundred two thousand, eight hundred thirty-one".