18661355953 has 2 divisors, whose sum is σ = 18661355954. Its totient is φ = 18661355952.

The previous prime is 18661355941. The next prime is 18661356013. The reversal of 18661355953 is 35955316681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12916777104 + 5744578849 = 113652^2 + 75793^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18661355953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18661355953.

It is not a weakly prime, because it can be changed into another prime (18661355353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9330677976 + 9330677977.

It is an arithmetic number, because the mean of its divisors is an integer number (9330677977).

Almost surely, 2^18661355953 is an apocalyptic number.

It is an amenable number.

18661355953 is a deficient number, since it is larger than the sum of its proper divisors (1).

18661355953 is an equidigital number, since it uses as much as digits as its factorization.

18661355953 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2916000, while the sum is 52.

The spelling of 18661355953 in words is "eighteen billion, six hundred sixty-one million, three hundred fifty-five thousand, nine hundred fifty-three".