18563994 has 24 divisors (see below), whose sum is σ = 40484340. Its totient is φ = 6147648.

The previous prime is 18563981. The next prime is 18564011. The reversal of 18563994 is 49936581.

It is a happy number.

18563994 is a `hidden beast` number, since 1 + 8 + 5 + 639 + 9 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 18275625 + 288369 = 4275^2 + 537^2 .

It is a congruent number.

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, 459 + ... + 6110.

Almost surely, 2^18563994 is an apocalyptic number.

18563994 is an abundant number, since it is smaller than the sum of its proper divisors (21920346).

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

18563994 is a wasteful number, since it uses less digits than its factorization.

18563994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6734 (or 6731 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 18563994 is about 4308.5953627604. The cubic root of 18563994 is about 264.7832284477.

The spelling of 18563994 in words is "eighteen million, five hundred sixty-three thousand, nine hundred ninety-four".