23813780021 has 2 divisors, whose sum is σ = 23813780022. Its totient is φ = 23813780020.

The previous prime is 23813779999. The next prime is 23813780027. The reversal of 23813780021 is 12008731832.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23806947025 + 6832996 = 154295^2 + 2614^2 .

It is a cyclic number.

It is not a de Polignac number, because 23813780021 - 2¹⁸ = 23813517877 is a prime.

It is a super-2 number, since 2×23813780021² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23813780027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11906890010 + 11906890011.

It is an arithmetic number, because the mean of its divisors is an integer number (11906890011).

Almost surely, 2^23813780021 is an apocalyptic number.

It is an amenable number.

23813780021 is a deficient number, since it is larger than the sum of its proper divisors (1).

23813780021 is an equidigital number, since it uses as much as digits as its factorization.

23813780021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 35.

The spelling of 23813780021 in words is "twenty-three billion, eight hundred thirteen million, seven hundred eighty thousand, twenty-one".