1645291440 has 200 divisors, whose sum is σ = 6154220688. Its totient is φ = 404974080.

The previous prime is 1645291421. The next prime is 1645291441. The reversal of 1645291440 is 441925461.

1645291440 is a `hidden beast` number, since 1 + 645 + 2 + 9 + 1 + 4 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1645291395 and 1645291404.

It is not an unprimeable number, because it can be changed into a prime (1645291441) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 74475 + ... + 94005.

Almost surely, 2^1645291440 is an apocalyptic number.

1645291440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1645291440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3077110344).

1645291440 is an abundant number, since it is smaller than the sum of its proper divisors (4508929248).

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

1645291440 is a wasteful number, since it uses less digits than its factorization.

1645291440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19569 (or 19554 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 1645291440 is about 40562.1922484473. The cubic root of 1645291440 is about 1180.5406504572.

The spelling of 1645291440 in words is "one billion, six hundred forty-five million, two hundred ninety-one thousand, four hundred forty".