1644646057 has 16 divisors (see below), whose sum is σ = 1720602000. Its totient is φ = 1570078720.

The previous prime is 1644646049. The next prime is 1644646067. The reversal of 1644646057 is 7506464461.

It can be written as a sum of positive squares in 8 ways, for example, as 12809241 + 1631836816 = 3579^2 + 40396^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644646057 - 2³ = 1644646049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644646067) 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, 1109757 + ... + 1111237.

It is an arithmetic number, because the mean of its divisors is an integer number (107537625).

Almost surely, 2^1644646057 is an apocalyptic number.

It is an amenable number.

1644646057 is a deficient number, since it is larger than the sum of its proper divisors (75955943).

1644646057 is a wasteful number, since it uses less digits than its factorization.

1644646057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1916.

The product of its (nonzero) digits is 483840, while the sum is 43.

The square root of 1644646057 is about 40554.2359932967. The cubic root of 1644646057 is about 1180.3862704101.

The spelling of 1644646057 in words is "one billion, six hundred forty-four million, six hundred forty-six thousand, fifty-seven".