21323510081 has 2 divisors, whose sum is σ = 21323510082. Its totient is φ = 21323510080.

The previous prime is 21323510029. The next prime is 21323510113. The reversal of 21323510081 is 18001532312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15355175056 + 5968335025 = 123916^2 + 77255^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323510081 - 2¹⁰ = 21323509057 is a prime.

It is a super-2 number, since 2×21323510081² (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 21323510081.

It is not a weakly prime, because it can be changed into another prime (21323510011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661755040 + 10661755041.

It is an arithmetic number, because the mean of its divisors is an integer number (10661755041).

Almost surely, 2^21323510081 is an apocalyptic number.

It is an amenable number.

21323510081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323510081 is an equidigital number, since it uses as much as digits as its factorization.

21323510081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 26.

The spelling of 21323510081 in words is "twenty-one billion, three hundred twenty-three million, five hundred ten thousand, eighty-one".