18639945 has 12 divisors (see below), whose sum is σ = 32309316. Its totient is φ = 9941280.

The previous prime is 18639911. The next prime is 18639949. The reversal of 18639945 is 54993681.

It is a happy number.

18639945 is a `hidden beast` number, since 1 + 8 + 639 + 9 + 4 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3732624 + 14907321 = 1932^2 + 3861^2 .

It is not a de Polignac number, because 18639945 - 2⁹ = 18639433 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 414221 = 18639945 / (1 + 8 + 6 + 3 + 9 + 9 + 4 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 18639945.

It is not an unprimeable number, because it can be changed into a prime (18639949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 207066 + ... + 207155.

It is an arithmetic number, because the mean of its divisors is an integer number (2692443).

Almost surely, 2^18639945 is an apocalyptic number.

18639945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18639945 is a deficient number, since it is larger than the sum of its proper divisors (13669371).

18639945 is a wasteful number, since it uses less digits than its factorization.

18639945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414232 (or 414229 counting only the distinct ones).

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

The square root of 18639945 is about 4317.4002594154. The cubic root of 18639945 is about 265.1438402680.

The spelling of 18639945 in words is "eighteen million, six hundred thirty-nine thousand, nine hundred forty-five".