1644567713649 has 81 divisors (see below), whose sum is σ = 2802368087883. Its totient is φ = 926657038944.

The previous prime is 1644567713647. The next prime is 1644567713681. The reversal of 1644567713649 is 9463177654461.

The square root of 1644567713649 is 1282407.

It is a perfect power (a square), and thus also a powerful number.

1644567713649 is a `hidden beast` number, since 1 + 6 + 4 + 4 + 567 + 7 + 1 + 3 + 64 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 104655485025 + 1539912228624 = 323505^2 + 1240932^2 .

It is not a de Polignac number, because 1644567713649 - 2¹ = 1644567713647 is a prime.

It is a super-3 number, since 3×1644567713649³ (a number of 38 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (1644567713647) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 2127512827 + ... + 2127513599.

Almost surely, 2^{1644567713649} is an apocalyptic number.

1644567713649 is the 1282407-th square number.

1644567713649 is the 641204-th centered octagonal number.

It is an amenable number.

1644567713649 is a deficient number, since it is larger than the sum of its proper divisors (1157800374234).

1644567713649 is an frugal number, since it uses more digits than its factorization.

1644567713649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1724 (or 862 counting only the distinct ones).

The product of its digits is 91445760, while the sum is 63.

The spelling of 1644567713649 in words is "one trillion, six hundred forty-four billion, five hundred sixty-seven million, seven hundred thirteen thousand, six hundred forty-nine".