991618218 has 12 divisors (see below), whose sum is σ = 2148506178. Its totient is φ = 330539400.

The previous prime is 991618217. The next prime is 991618231. The reversal of 991618218 is 812816199.

991618218 is a `hidden beast` number, since 9 + 9 + 1 + 618 + 21 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 607967649 + 383650569 = 24657^2 + 19587^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (991618217) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27544933 + ... + 27544968.

Almost surely, 2^991618218 is an apocalyptic number.

991618218 is an abundant number, since it is smaller than the sum of its proper divisors (1156887960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991618218 is a wasteful number, since it uses less digits than its factorization.

991618218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55089909 (or 55089906 counting only the distinct ones).

The product of its digits is 62208, while the sum is 45.

The square root of 991618218 is about 31489.9701174834. The cubic root of 991618218 is about 997.1982300832.

The spelling of 991618218 in words is "nine hundred ninety-one million, six hundred eighteen thousand, two hundred eighteen".