1644423245 has 4 divisors (see below), whose sum is σ = 1973307900. Its totient is φ = 1315538592.

The previous prime is 1644423211. The next prime is 1644423251. The reversal of 1644423245 is 5423244461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5423244461 = 19 ⋅285433919.

It can be written as a sum of positive squares in 2 ways, for example, as 205434889 + 1438988356 = 14333^2 + 37934^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644423245 - 2¹⁴ = 1644406861 is a prime.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 164442320 + ... + 164442329.

It is an arithmetic number, because the mean of its divisors is an integer number (493326975).

Almost surely, 2^1644423245 is an apocalyptic number.

It is an amenable number.

1644423245 is a deficient number, since it is larger than the sum of its proper divisors (328884655).

1644423245 is an equidigital number, since it uses as much as digits as its factorization.

1644423245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328884654.

The product of its digits is 92160, while the sum is 35.

The square root of 1644423245 is about 40551.4888136058. The cubic root of 1644423245 is about 1180.3329628707.

The spelling of 1644423245 in words is "one billion, six hundred forty-four million, four hundred twenty-three thousand, two hundred forty-five".