1638225 has 30 divisors (see below), whose sum is σ = 3038310. Its totient is φ = 872640.

The previous prime is 1638211. The next prime is 1638251. The reversal of 1638225 is 5228361.

1638225 is a `hidden beast` number, since 1 + 638 + 2 + 25 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 331776 + 1306449 = 576^2 + 1143^2 .

It is not a de Polignac number, because 1638225 - 2⁴ = 1638209 is a prime.

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

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 29 ways as a sum of consecutive naturals, for example, 1621 + ... + 2429.

It is an arithmetic number, because the mean of its divisors is an integer number (101277).

2^1638225 is an apocalyptic number.

1638225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1638225 is a deficient number, since it is larger than the sum of its proper divisors (1400085).

1638225 is an equidigital number, since it uses as much as digits as its factorization.

1638225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 831 (or 817 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 1638225 is about 1279.9316387995. The cubic root of 1638225 is about 117.8848105055.

The spelling of 1638225 in words is "one million, six hundred thirty-eight thousand, two hundred twenty-five".