18991910 has 48 divisors (see below), whose sum is σ = 40235616. Its totient is φ = 6453888.

The previous prime is 18991909. The next prime is 18991913. The reversal of 18991910 is 1919981.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18991913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 168014 + ... + 168126.

It is an arithmetic number, because the mean of its divisors is an integer number (838242).

Almost surely, 2^18991910 is an apocalyptic number.

18991910 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18991910 is an abundant number, since it is smaller than the sum of its proper divisors (21243706).

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

18991910 is an frugal number, since it uses more digits than its factorization.

18991910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155 (or 127 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 38.

The square root of 18991910 is about 4357.9708580944. The cubic root of 18991910 is about 266.8022869179.

The spelling of 18991910 in words is "eighteen million, nine hundred ninety-one thousand, nine hundred ten".