1645731648 has 336 divisors, whose sum is σ = 5642945280. Its totient is φ = 468357120.

The previous prime is 1645731623. The next prime is 1645731667. The reversal of 1645731648 is 8461375461.

1645731648 is a `hidden beast` number, since 1 + 64 + 573 + 16 + 4 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3554265 + ... + 3554727.

It is an arithmetic number, because the mean of its divisors is an integer number (16794480).

Almost surely, 2^1645731648 is an apocalyptic number.

1645731648 is a gapful number since it is divisible by the number (18) 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 1645731648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2821472640).

1645731648 is an abundant number, since it is smaller than the sum of its proper divisors (3997213632).

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

1645731648 is a wasteful number, since it uses less digits than its factorization.

1645731648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523 (or 496 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The square root of 1645731648 is about 40567.6182194617. The cubic root of 1645731648 is about 1180.6459280764.

The spelling of 1645731648 in words is "one billion, six hundred forty-five million, seven hundred thirty-one thousand, six hundred forty-eight".