18817999997 has 2 divisors, whose sum is σ = 18817999998. Its totient is φ = 18817999996.

The previous prime is 18817999951. The next prime is 18818000011. The reversal of 18817999997 is 79999971881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15552334681 + 3265665316 = 124709^2 + 57146^2 .

It is a cyclic number.

It is not a de Polignac number, because 18817999997 - 2²² = 18813805693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18817999597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9408999998 + 9408999999.

It is an arithmetic number, because the mean of its divisors is an integer number (9408999999).

Almost surely, 2^18817999997 is an apocalyptic number.

It is an amenable number.

18817999997 is a deficient number, since it is larger than the sum of its proper divisors (1).

18817999997 is an equidigital number, since it uses as much as digits as its factorization.

18817999997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 185177664, while the sum is 77.

The spelling of 18817999997 in words is "eighteen billion, eight hundred seventeen million, nine hundred ninety-nine thousand, nine hundred ninety-seven".