18621666 has 72 divisors (see below), whose sum is σ = 48123504. Its totient is φ = 5186160.

The previous prime is 18621661. The next prime is 18621671. The reversal of 18621666 is 66612681.

It is an interprime number because it is at equal distance from previous prime (18621661) and next prime (18621671).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18621666.

It is not an unprimeable number, because it can be changed into a prime (18621661) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 37681 + ... + 38171.

It is an arithmetic number, because the mean of its divisors is an integer number (668382).

Almost surely, 2^18621666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18621666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24061752).

18621666 is an abundant number, since it is smaller than the sum of its proper divisors (29501838).

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

18621666 is a wasteful number, since it uses less digits than its factorization.

18621666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 556 (or 546 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 18621666 is about 4315.2828412515. The cubic root of 18621666 is about 265.0571420623.

The spelling of 18621666 in words is "eighteen million, six hundred twenty-one thousand, six hundred sixty-six".