1921981440 has 176 divisors, whose sum is σ = 6194254752. Its totient is φ = 508624896.

The previous prime is 1921981349. The next prime is 1921981469. The reversal of 1921981440 is 441891291.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2411122 + ... + 2411918.

Almost surely, 2^1921981440 is an apocalyptic number.

1921981440 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 1921981440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3097127376).

1921981440 is an abundant number, since it is smaller than the sum of its proper divisors (4272273312).

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

1921981440 is a wasteful number, since it uses less digits than its factorization.

1921981440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982 (or 964 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 1921981440 is about 43840.4087572185. The cubic root of 1921981440 is about 1243.3204105796.

The spelling of 1921981440 in words is "one billion, nine hundred twenty-one million, nine hundred eighty-one thousand, four hundred forty".