18639428 has 6 divisors (see below), whose sum is σ = 32619006. Its totient is φ = 9319712.

The previous prime is 18639421. The next prime is 18639433. The reversal of 18639428 is 82493681.

It can be written as a sum of positive squares in only one way, i.e., 17455684 + 1183744 = 4178^2 + 1088^2 .

It is not an unprimeable number, because it can be changed into a prime (18639421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2329925 + ... + 2329932.

It is an arithmetic number, because the mean of its divisors is an integer number (5436501).

Almost surely, 2^18639428 is an apocalyptic number.

It is an amenable number.

18639428 is a deficient number, since it is larger than the sum of its proper divisors (13979578).

18639428 is a wasteful number, since it uses less digits than its factorization.

18639428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4659861 (or 4659859 counting only the distinct ones).

The product of its digits is 82944, while the sum is 41.

The square root of 18639428 is about 4317.3403850056. The cubic root of 18639428 is about 265.1413888903.

The spelling of 18639428 in words is "eighteen million, six hundred thirty-nine thousand, four hundred twenty-eight".