1921565880 has 384 divisors, whose sum is σ = 7019550720. Its totient is φ = 452874240.

The previous prime is 1921565873. The next prime is 1921565929. The reversal of 1921565880 is 885651291.

It is a happy number.

1921565880 is a `hidden beast` number, since 1 + 9 + 2 + 1 + 565 + 8 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 15130377 + ... + 15130503.

It is an arithmetic number, because the mean of its divisors is an integer number (18280080).

Almost surely, 2^1921565880 is an apocalyptic number.

1921565880 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 1921565880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3509775360).

1921565880 is an abundant number, since it is smaller than the sum of its proper divisors (5097984840).

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

1921565880 is a wasteful number, since it uses less digits than its factorization.

1921565880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271 (or 264 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 45.

The square root of 1921565880 is about 43835.6690378965. The cubic root of 1921565880 is about 1243.2307962089.

The spelling of 1921565880 in words is "one billion, nine hundred twenty-one million, five hundred sixty-five thousand, eight hundred eighty".