18724428 has 18 divisors (see below), whose sum is σ = 47331284. Its totient is φ = 6241464.

The previous prime is 18724399. The next prime is 18724451. The reversal of 18724428 is 82442781.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 520123 = 18724428 / (1 + 8 + 7 + 2 + 4 + 4 + 2 + 8).

It is a junction number, because it is equal to n+sod(n) for n = 18724392 and 18724401.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 260026 + ... + 260097.

Almost surely, 2^18724428 is an apocalyptic number.

18724428 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

18724428 is an abundant number, since it is smaller than the sum of its proper divisors (28606856).

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

18724428 is a wasteful number, since it uses less digits than its factorization.

18724428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520133 (or 520128 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 18724428 is about 4327.1732112316. The cubic root of 18724428 is about 265.5438126596.

The spelling of 18724428 in words is "eighteen million, seven hundred twenty-four thousand, four hundred twenty-eight".