18378820 has 24 divisors (see below), whose sum is σ = 38677464. Its totient is φ = 7335936.

The previous prime is 18378803. The next prime is 18378821. The reversal of 18378820 is 2887381.

It can be written as a sum of positive squares in 4 ways, for example, as 3755844 + 14622976 = 1938^2 + 3824^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18378820.

It is not an unprimeable number, because it can be changed into a prime (18378821) 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, 15364 + ... + 16516.

It is an arithmetic number, because the mean of its divisors is an integer number (1611561).

Almost surely, 2^18378820 is an apocalyptic number.

18378820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18378820 is an abundant number, since it is smaller than the sum of its proper divisors (20298644).

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

18378820 is a wasteful number, since it uses less digits than its factorization.

18378820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1959 (or 1957 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 18378820 is about 4287.0526005637. The cubic root of 18378820 is about 263.8998893455.

It can be divided in two parts, 183 and 78820, that added together give a triangular number (79003 = T₃₉₇).

The spelling of 18378820 in words is "eighteen million, three hundred seventy-eight thousand, eight hundred twenty".