18156820 has 24 divisors (see below), whose sum is σ = 41596128. Its totient is φ = 6602400.

The previous prime is 18156797. The next prime is 18156823. The reversal of 18156820 is 2865181.

It is a super-2 number, since 2×18156820² = 659340225024800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18156823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41046 + ... + 41485.

It is an arithmetic number, because the mean of its divisors is an integer number (1733172).

Almost surely, 2^18156820 is an apocalyptic number.

18156820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18156820 is an abundant number, since it is smaller than the sum of its proper divisors (23439308).

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

18156820 is a wasteful number, since it uses less digits than its factorization.

18156820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82551 (or 82549 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 18156820 is about 4261.0820222099. The cubic root of 18156820 is about 262.8330225302.

The spelling of 18156820 in words is "eighteen million, one hundred fifty-six thousand, eight hundred twenty".