23281787561 has 2 divisors, whose sum is σ = 23281787562. Its totient is φ = 23281787560.

The previous prime is 23281787533. The next prime is 23281787593. The reversal of 23281787561 is 16578718232.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12126414400 + 11155373161 = 110120^2 + 105619^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23281787561 is a prime.

It is not a weakly prime, because it can be changed into another prime (23281087561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11640893780 + 11640893781.

It is an arithmetic number, because the mean of its divisors is an integer number (11640893781).

Almost surely, 2^23281787561 is an apocalyptic number.

It is an amenable number.

23281787561 is a deficient number, since it is larger than the sum of its proper divisors (1).

23281787561 is an equidigital number, since it uses as much as digits as its factorization.

23281787561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1128960, while the sum is 50.

The spelling of 23281787561 in words is "twenty-three billion, two hundred eighty-one million, seven hundred eighty-seven thousand, five hundred sixty-one".