18491918 has 4 divisors (see below), whose sum is σ = 27737880. Its totient is φ = 9245958.

The previous prime is 18491917. The next prime is 18491927. The reversal of 18491918 is 81919481.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18491911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4622978 + ... + 4622981.

It is an arithmetic number, because the mean of its divisors is an integer number (6934470).

Almost surely, 2^18491918 is an apocalyptic number.

18491918 is a deficient number, since it is larger than the sum of its proper divisors (9245962).

18491918 is an equidigital number, since it uses as much as digits as its factorization.

18491918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9245961.

The product of its digits is 20736, while the sum is 41.

The square root of 18491918 is about 4300.2230174725. The cubic root of 18491918 is about 264.4401042188.

The spelling of 18491918 in words is "eighteen million, four hundred ninety-one thousand, nine hundred eighteen".