18625221 has 28 divisors (see below), whose sum is σ = 28920780. Its totient is φ = 11975040.

The previous prime is 18625219. The next prime is 18625231. The reversal of 18625221 is 12252681.

It is a happy number.

18625221 is a `hidden beast` number, since 18 + 625 + 2 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6305121 + 12320100 = 2511^2 + 3510^2 .

It is not a de Polignac number, because 18625221 - 2¹ = 18625219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18625231) 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 27 ways as a sum of consecutive naturals, for example, 20701 + ... + 21581.

It is an arithmetic number, because the mean of its divisors is an integer number (1032885).

Almost surely, 2^18625221 is an apocalyptic number.

It is an amenable number.

18625221 is a deficient number, since it is larger than the sum of its proper divisors (10295559).

18625221 is an frugal number, since it uses more digits than its factorization.

18625221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 928 (or 913 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 18625221 is about 4315.6947297046. The cubic root of 18625221 is about 265.0740080466.

The spelling of 18625221 in words is "eighteen million, six hundred twenty-five thousand, two hundred twenty-one".