18921240 has 144 divisors (see below), whose sum is σ = 66802320. Its totient is φ = 4642560.

The previous prime is 18921233. The next prime is 18921251. The reversal of 18921240 is 4212981.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 60685 + ... + 60995.

It is an arithmetic number, because the mean of its divisors is an integer number (463905).

Almost surely, 2^18921240 is an apocalyptic number.

18921240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18921240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33401160).

18921240 is an abundant number, since it is smaller than the sum of its proper divisors (47881080).

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

18921240 is a wasteful number, since it uses less digits than its factorization.

18921240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 18921240 is about 4349.8551700028. The cubic root of 18921240 is about 266.4709466642.

The spelling of 18921240 in words is "eighteen million, nine hundred twenty-one thousand, two hundred forty".