18261720 has 128 divisors (see below), whose sum is σ = 62654400. Its totient is φ = 4727808.

The previous prime is 18261673. The next prime is 18261731. The reversal of 18261720 is 2716281.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 39732 + ... + 40188.

Almost surely, 2^18261720 is an apocalyptic number.

18261720 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 18261720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31327200).

18261720 is an abundant number, since it is smaller than the sum of its proper divisors (44392680).

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

18261720 is a wasteful number, since it uses less digits than its factorization.

18261720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514 (or 504 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 18261720 is about 4273.3733747474. The cubic root of 18261720 is about 263.3382184997.

It can be divided in two parts, 18261 and 720, that added together give a palindrome (18981).

The spelling of 18261720 in words is "eighteen million, two hundred sixty-one thousand, seven hundred twenty".