18213812 has 6 divisors (see below), whose sum is σ = 31874178. Its totient is φ = 9106904.

The previous prime is 18213803. The next prime is 18213823. The reversal of 18213812 is 21831281.

It can be written as a sum of positive squares in only one way, i.e., 15792676 + 2421136 = 3974^2 + 1556^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2276723 + ... + 2276730.

It is an arithmetic number, because the mean of its divisors is an integer number (5312363).

Almost surely, 2^18213812 is an apocalyptic number.

It is an amenable number.

18213812 is a deficient number, since it is larger than the sum of its proper divisors (13660366).

18213812 is a wasteful number, since it uses less digits than its factorization.

18213812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4553457 (or 4553455 counting only the distinct ones).

The product of its digits is 768, while the sum is 26.

The square root of 18213812 is about 4267.7642858996. The cubic root of 18213812 is about 263.1077353578.

The spelling of 18213812 in words is "eighteen million, two hundred thirteen thousand, eight hundred twelve".