18911550 has 144 divisors (see below), whose sum is σ = 56996352. Its totient is φ = 4132800.

The previous prime is 18911549. The next prime is 18911591. The reversal of 18911550 is 5511981.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 227809 + ... + 227891.

It is an arithmetic number, because the mean of its divisors is an integer number (395808).

Almost surely, 2^18911550 is an apocalyptic number.

18911550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18911550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28498176).

18911550 is an abundant number, since it is smaller than the sum of its proper divisors (38084802).

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

18911550 is a wasteful number, since it uses less digits than its factorization.

18911550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143 (or 131 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 30.

The square root of 18911550 is about 4348.7411971742. The cubic root of 18911550 is about 266.4254502735.

The spelling of 18911550 in words is "eighteen million, nine hundred eleven thousand, five hundred fifty".