1644256544 has 36 divisors (see below), whose sum is σ = 3765644694. Its totient is φ = 704680704.

The previous prime is 1644256531. The next prime is 1644256547. The reversal of 1644256544 is 4456524461.

It can be written as a sum of positive squares in only one way, i.e., 1600960144 + 43296400 = 40012^2 + 6580^2 .

It is a super-3 number, since 3×1644256544³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1644256547) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 522749 + ... + 525884.

Almost surely, 2^1644256544 is an apocalyptic number.

1644256544 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

1644256544 is an abundant number, since it is smaller than the sum of its proper divisors (2121388150).

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

1644256544 is a wasteful number, since it uses less digits than its factorization.

1644256544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1048657 (or 1048642 counting only the distinct ones).

The product of its digits is 460800, while the sum is 41.

The square root of 1644256544 is about 40549.4333375943. The cubic root of 1644256544 is about 1180.2930766806.

The spelling of 1644256544 in words is "one billion, six hundred forty-four million, two hundred fifty-six thousand, five hundred forty-four".