1644445572 has 48 divisors (see below), whose sum is σ = 4783844352. Its totient is φ = 427128480.

The previous prime is 1644445571. The next prime is 1644445577. The reversal of 1644445572 is 2755444461.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (1644445571) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 888928 + ... + 890775.

It is an arithmetic number, because the mean of its divisors is an integer number (99663424).

Almost surely, 2^1644445572 is an apocalyptic number.

1644445572 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1644445572 is an abundant number, since it is smaller than the sum of its proper divisors (3139398780).

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

1644445572 is a wasteful number, since it uses less digits than its factorization.

1644445572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1779728 (or 1779726 counting only the distinct ones).

The product of its digits is 537600, while the sum is 42.

The square root of 1644445572 is about 40551.7641046601. The cubic root of 1644445572 is about 1180.3383047993.

The spelling of 1644445572 in words is "one billion, six hundred forty-four million, four hundred forty-five thousand, five hundred seventy-two".