18021780 has 72 divisors (see below), whose sum is σ = 62479872. Its totient is φ = 4118976.

The previous prime is 18021763. The next prime is 18021781. The reversal of 18021780 is 8712081.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5892 + ... + 8411.

It is an arithmetic number, because the mean of its divisors is an integer number (867776).

Almost surely, 2^18021780 is an apocalyptic number.

18021780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18021780 is an abundant number, since it is smaller than the sum of its proper divisors (44458092).

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

18021780 is a wasteful number, since it uses less digits than its factorization.

18021780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14325 (or 14320 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 18021780 is about 4245.2067087481. The cubic root of 18021780 is about 262.1798000521.

It can be divided in two parts, 180 and 21780, that multiplied together give a square (3920400 = 1980²).

The spelling of 18021780 in words is "eighteen million, twenty-one thousand, seven hundred eighty".