19998666 has 24 divisors (see below), whose sum is σ = 43732260. Its totient is φ = 6604416.

The previous prime is 19998653. The next prime is 19998677. The reversal of 19998666 is 66689991.

It can be written as a sum of positive squares in 2 ways, for example, as 19105641 + 893025 = 4371^2 + 945^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3135 + ... + 7058.

Almost surely, 2^19998666 is an apocalyptic number.

19998666 is an abundant number, since it is smaller than the sum of its proper divisors (23733594).

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

19998666 is a wasteful number, since it uses less digits than its factorization.

19998666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10310 (or 10307 counting only the distinct ones).

The product of its digits is 1259712, while the sum is 54.

The square root of 19998666 is about 4471.9868067784. The cubic root of 19998666 is about 271.4357264701.

The spelling of 19998666 in words is "nineteen million, nine hundred ninety-eight thousand, six hundred sixty-six".