818881997 has 2 divisors, whose sum is σ = 818881998. Its totient is φ = 818881996.

The previous prime is 818881991. The next prime is 818882069. The reversal of 818881997 is 799188818.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 551592196 + 267289801 = 23486^2 + 16349^2 .

It is a cyclic number.

It is not a de Polignac number, because 818881997 - 2⁶ = 818881933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (818881991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409440998 + 409440999.

It is an arithmetic number, because the mean of its divisors is an integer number (409440999).

Almost surely, 2^818881997 is an apocalyptic number.

It is an amenable number.

818881997 is a deficient number, since it is larger than the sum of its proper divisors (1).

818881997 is an equidigital number, since it uses as much as digits as its factorization.

818881997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2322432, while the sum is 59.

The square root of 818881997 is about 28616.1142889806. The cubic root of 818881997 is about 935.5645868066.

The spelling of 818881997 in words is "eight hundred eighteen million, eight hundred eighty-one thousand, nine hundred ninety-seven".