21320023531 has 2 divisors, whose sum is σ = 21320023532. Its totient is φ = 21320023530.

The previous prime is 21320023523. The next prime is 21320023547. The reversal of 21320023531 is 13532002312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21320023531 - 2³ = 21320023523 is a prime.

It is a super-2 number, since 2×21320023531² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21320023511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660011765 + 10660011766.

It is an arithmetic number, because the mean of its divisors is an integer number (10660011766).

Almost surely, 2^21320023531 is an apocalyptic number.

21320023531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320023531 is an equidigital number, since it uses as much as digits as its factorization.

21320023531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 22.

Adding to 21320023531 its reverse (13532002312), we get a palindrome (34852025843).

The spelling of 21320023531 in words is "twenty-one billion, three hundred twenty million, twenty-three thousand, five hundred thirty-one".