1645331640 has 128 divisors (see below), whose sum is σ = 5095379520. Its totient is φ = 424755200.

The previous prime is 1645331627. The next prime is 1645331647. The reversal of 1645331640 is 461335461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645331647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 672820 + ... + 675260.

Almost surely, 2^1645331640 is an apocalyptic number.

1645331640 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 1645331640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2547689760).

1645331640 is an abundant number, since it is smaller than the sum of its proper divisors (3450047880).

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

1645331640 is a wasteful number, since it uses less digits than its factorization.

1645331640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2633 (or 2629 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 1645331640 is about 40562.6877807672. The cubic root of 1645331640 is about 1180.5502652376.

The spelling of 1645331640 in words is "one billion, six hundred forty-five million, three hundred thirty-one thousand, six hundred forty".