18525221 has 12 divisors (see below), whose sum is σ = 21930636. Its totient is φ = 15544320.

The previous prime is 18525203. The next prime is 18525239. The reversal of 18525221 is 12252581.

It is an interprime number because it is at equal distance from previous prime (18525203) and next prime (18525239).

It can be written as a sum of positive squares in 2 ways, for example, as 7562500 + 10962721 = 2750^2 + 3311^2 .

It is not a de Polignac number, because 18525221 - 2²² = 14330917 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18525821) 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, 4316 + ... + 7461.

It is an arithmetic number, because the mean of its divisors is an integer number (1827553).

Almost surely, 2^18525221 is an apocalyptic number.

18525221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18525221 is a deficient number, since it is larger than the sum of its proper divisors (3405415).

18525221 is a wasteful number, since it uses less digits than its factorization.

18525221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11812 (or 11801 counting only the distinct ones).

The product of its digits is 1600, while the sum is 26.

The square root of 18525221 is about 4304.0935166420. The cubic root of 18525221 is about 264.5987567231.

The spelling of 18525221 in words is "eighteen million, five hundred twenty-five thousand, two hundred twenty-one".