18261820 has 24 divisors (see below), whose sum is σ = 38631600. Its totient is φ = 7251072.

The previous prime is 18261809. The next prime is 18261827. The reversal of 18261820 is 2816281.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18261827) 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 7 ways as a sum of consecutive naturals, for example, 505 + ... + 6064.

It is an arithmetic number, because the mean of its divisors is an integer number (1609650).

Almost surely, 2^18261820 is an apocalyptic number.

18261820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18261820 is an abundant number, since it is smaller than the sum of its proper divisors (20369780).

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

18261820 is a wasteful number, since it uses less digits than its factorization.

18261820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6717 (or 6715 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 18261820 is about 4273.3850750898. The cubic root of 18261820 is about 263.3386991732.

The spelling of 18261820 in words is "eighteen million, two hundred sixty-one thousand, eight hundred twenty".