1921328640 has 960 divisors, whose sum is σ = 8980139520. Its totient is φ = 378224640.

The previous prime is 1921328639. The next prime is 1921328699. The reversal of 1921328640 is 468231291.

1921328640 is a `hidden beast` number, since 1 + 9 + 2 + 1 + 3 + 2 + 8 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

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 = 1921328595 and 1921328604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 101122551 + ... + 101122569.

It is an arithmetic number, because the mean of its divisors is an integer number (9354312).

Almost surely, 2^1921328640 is an apocalyptic number.

1921328640 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 1921328640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4490069760).

1921328640 is an abundant number, since it is smaller than the sum of its proper divisors (7058810880).

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

1921328640 is a wasteful number, since it uses less digits than its factorization.

1921328640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 1921328640 is about 43832.9629388660. The cubic root of 1921328640 is about 1243.1796302621.

The spelling of 1921328640 in words is "one billion, nine hundred twenty-one million, three hundred twenty-eight thousand, six hundred forty".