1645444644 has 24 divisors (see below), whose sum is σ = 3840049248. Its totient is φ = 548384640.

The previous prime is 1645444643. The next prime is 1645444657. The reversal of 1645444644 is 4464445461.

It is a junction number, because it is equal to n+sod(n) for n = 1645444596 and 1645444605.

It is not an unprimeable number, because it can be changed into a prime (1645444643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 100524 + ... + 115740.

It is an arithmetic number, because the mean of its divisors is an integer number (160002052).

Almost surely, 2^1645444644 is an apocalyptic number.

It is an amenable number.

1645444644 is an abundant number, since it is smaller than the sum of its proper divisors (2194604604).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1645444644 is a wasteful number, since it uses less digits than its factorization.

1645444644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24235 (or 24233 counting only the distinct ones).

The product of its digits is 737280, while the sum is 42.

The square root of 1645444644 is about 40564.0807118810. The cubic root of 1645444644 is about 1180.5772919769.

The spelling of 1645444644 in words is "one billion, six hundred forty-five million, four hundred forty-four thousand, six hundred forty-four".