18419991 has 8 divisors (see below), whose sum is σ = 25023600. Its totient is φ = 12048192.

The previous prime is 18419981. The next prime is 18420007. The reversal of 18419991 is 19991481.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18419991 - 2⁶ = 18419927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18419981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57766 + ... + 58083.

It is an arithmetic number, because the mean of its divisors is an integer number (3127950).

Almost surely, 2^18419991 is an apocalyptic number.

18419991 is a deficient number, since it is larger than the sum of its proper divisors (6603609).

18419991 is a wasteful number, since it uses less digits than its factorization.

18419991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115905.

The product of its digits is 23328, while the sum is 42.

The square root of 18419991 is about 4291.8516982766. The cubic root of 18419991 is about 264.0967993283.

The spelling of 18419991 in words is "eighteen million, four hundred nineteen thousand, nine hundred ninety-one".