18309816 has 96 divisors (see below), whose sum is σ = 60035040. Its totient is φ = 4921344.

The previous prime is 18309803. The next prime is 18309829. The reversal of 18309816 is 61890381.

It is an interprime number because it is at equal distance from previous prime (18309803) and next prime (18309829).

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

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7500 + ... + 9636.

It is an arithmetic number, because the mean of its divisors is an integer number (625365).

Almost surely, 2^18309816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18309816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30017520).

18309816 is an abundant number, since it is smaller than the sum of its proper divisors (41725224).

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

18309816 is a wasteful number, since it uses less digits than its factorization.

18309816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2173 (or 2166 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 18309816 is about 4278.9970787557. The cubic root of 18309816 is about 263.5692009796.

The spelling of 18309816 in words is "eighteen million, three hundred nine thousand, eight hundred sixteen".