23661388781 has 2 divisors, whose sum is σ = 23661388782. Its totient is φ = 23661388780.

The previous prime is 23661388661. The next prime is 23661388837. The reversal of 23661388781 is 18788316632.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18180207556 + 5481181225 = 134834^2 + 74035^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23661388781 is a prime.

It is a super-2 number, since 2×23661388781² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23661388181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11830694390 + 11830694391.

It is an arithmetic number, because the mean of its divisors is an integer number (11830694391).

Almost surely, 2^23661388781 is an apocalyptic number.

It is an amenable number.

23661388781 is a deficient number, since it is larger than the sum of its proper divisors (1).

23661388781 is an equidigital number, since it uses as much as digits as its factorization.

23661388781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2322432, while the sum is 53.

The spelling of 23661388781 in words is "twenty-three billion, six hundred sixty-one million, three hundred eighty-eight thousand, seven hundred eighty-one".