18991116 has 36 divisors (see below), whose sum is σ = 48141912. Its totient is φ = 6312384.

The previous prime is 18991081. The next prime is 18991117. The reversal of 18991116 is 61119981.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (18991117) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19800 + ... + 20736.

Almost surely, 2^18991116 is an apocalyptic number.

It is an amenable number.

18991116 is an abundant number, since it is smaller than the sum of its proper divisors (29150796).

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

18991116 is a wasteful number, since it uses less digits than its factorization.

18991116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1510 (or 1505 counting only the distinct ones).

The product of its digits is 3888, while the sum is 36.

The square root of 18991116 is about 4357.8797596997. The cubic root of 18991116 is about 266.7985687739.

The spelling of 18991116 in words is "eighteen million, nine hundred ninety-one thousand, one hundred sixteen".