18901890 has 128 divisors (see below), whose sum is σ = 58821120. Its totient is φ = 4230144.

The previous prime is 18901877. The next prime is 18901891. The reversal of 18901890 is 9810981.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18901891) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 137902 + ... + 138038.

It is an arithmetic number, because the mean of its divisors is an integer number (459540).

Almost surely, 2^18901890 is an apocalyptic number.

18901890 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 18901890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29410560).

18901890 is an abundant number, since it is smaller than the sum of its proper divisors (39919230).

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

18901890 is a wasteful number, since it uses less digits than its factorization.

18901890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233 (or 227 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 18901890 is about 4347.6303890740. The cubic root of 18901890 is about 266.3800792668.

Subtracting from 18901890 its reverse (9810981), we obtain a palindrome (9090909).

It can be divided in two parts, 18901 and 890, that added together give a palindrome (19791).

The spelling of 18901890 in words is "eighteen million, nine hundred one thousand, eight hundred ninety".