1645904640 has 288 divisors, whose sum is σ = 5863173120. Its totient is φ = 391053312.

The previous prime is 1645904629. The next prime is 1645904653. The reversal of 1645904640 is 464095461.

1645904640 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1239657 + ... + 1240983.

It is an arithmetic number, because the mean of its divisors is an integer number (20358240).

Almost surely, 2^1645904640 is an apocalyptic number.

1645904640 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 1645904640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2931586560).

1645904640 is an abundant number, since it is smaller than the sum of its proper divisors (4217268480).

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

1645904640 is a wasteful number, since it uses less digits than its factorization.

1645904640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1387 (or 1373 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The square root of 1645904640 is about 40569.7503073411. The cubic root of 1645904640 is about 1180.6872947121.

The spelling of 1645904640 in words is "one billion, six hundred forty-five million, nine hundred four thousand, six hundred forty".