1645720768 has 112 divisors (see below), whose sum is σ = 3663269280. Its totient is φ = 729759744.

The previous prime is 1645720759. The next prime is 1645720781. The reversal of 1645720768 is 8670275461.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1356130 + ... + 1357342.

Almost surely, 2^1645720768 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1645720768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1831634640).

1645720768 is an abundant number, since it is smaller than the sum of its proper divisors (2017548512).

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

1645720768 is a wasteful number, since it uses less digits than its factorization.

1645720768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1314 (or 1304 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 46.

The square root of 1645720768 is about 40567.4841221390. The cubic root of 1645720768 is about 1180.6433263043.

The spelling of 1645720768 in words is "one billion, six hundred forty-five million, seven hundred twenty thousand, seven hundred sixty-eight".