18219780 has 36 divisors (see below), whose sum is σ = 55267212. Its totient is φ = 4858560.

The previous prime is 18219763. The next prime is 18219787. The reversal of 18219780 is 8791281.

It can be written as a sum of positive squares in 2 ways, for example, as 2585664 + 15634116 = 1608^2 + 3954^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18219787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50431 + ... + 50790.

Almost surely, 2^18219780 is an apocalyptic number.

18219780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18219780 is an abundant number, since it is smaller than the sum of its proper divisors (37047432).

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

18219780 is a wasteful number, since it uses less digits than its factorization.

18219780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101236 (or 101231 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 18219780 is about 4268.4634237627. The cubic root of 18219780 is about 263.1364691469.

The spelling of 18219780 in words is "eighteen million, two hundred nineteen thousand, seven hundred eighty".