18425221 has 2 divisors, whose sum is σ = 18425222. Its totient is φ = 18425220.

The previous prime is 18425207. The next prime is 18425261. The reversal of 18425221 is 12252481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11296321 + 7128900 = 3361^2 + 2670^2 .

It is a cyclic number.

It is not a de Polignac number, because 18425221 - 2⁵ = 18425189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18425261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9212610 + 9212611.

It is an arithmetic number, because the mean of its divisors is an integer number (9212611).

Almost surely, 2^18425221 is an apocalyptic number.

It is an amenable number.

18425221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18425221 is an equidigital number, since it uses as much as digits as its factorization.

18425221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1280, while the sum is 25.

The square root of 18425221 is about 4292.4609491526. The cubic root of 18425221 is about 264.1217920216.

The spelling of 18425221 in words is "eighteen million, four hundred twenty-five thousand, two hundred twenty-one".