21023023381 has 2 divisors, whose sum is σ = 21023023382. Its totient is φ = 21023023380.

The previous prime is 21023023367. The next prime is 21023023397. The reversal of 21023023381 is 18332032012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20376135025 + 646888356 = 142745^2 + 25434^2 .

It is a cyclic number.

It is not a de Polignac number, because 21023023381 - 2⁵ = 21023023349 is a prime.

It is a super-2 number, since 2×21023023381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21023023321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511511690 + 10511511691.

It is an arithmetic number, because the mean of its divisors is an integer number (10511511691).

Almost surely, 2^21023023381 is an apocalyptic number.

It is an amenable number.

21023023381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21023023381 is an equidigital number, since it uses as much as digits as its factorization.

21023023381 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 25.

Adding to 21023023381 its reverse (18332032012), we get a palindrome (39355055393).

The spelling of 21023023381 in words is "twenty-one billion, twenty-three million, twenty-three thousand, three hundred eighty-one".