1644745225 has 6 divisors (see below), whose sum is σ = 2039484110. Its totient is φ = 1315796160.

The previous prime is 1644745199. The next prime is 1644745231. The reversal of 1644745225 is 5225474461.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 18800896 + 1625944329 = 4336^2 + 40323^2 .

It is not a de Polignac number, because 1644745225 - 2¹⁵ = 1644712457 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32894880 + ... + 32894929.

Almost surely, 2^1644745225 is an apocalyptic number.

It is an amenable number.

1644745225 is a deficient number, since it is larger than the sum of its proper divisors (394738885).

1644745225 is an equidigital number, since it uses as much as digits as its factorization.

1644745225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65789819 (or 65789814 counting only the distinct ones).

The product of its digits is 268800, while the sum is 40.

The square root of 1644745225 is about 40555.4586338263. The cubic root of 1644745225 is about 1180.4099947028.

The spelling of 1644745225 in words is "one billion, six hundred forty-four million, seven hundred forty-five thousand, two hundred twenty-five".