815721984 has 480 divisors, whose sum is σ = 3115157760. Its totient is φ = 200724480.

The previous prime is 815721983. The next prime is 815722001. The reversal of 815721984 is 489127518.

Its product of digits (161280) is a multiple of the sum of its prime divisors (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815721983) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 42932727 + ... + 42932745.

It is an arithmetic number, because the mean of its divisors is an integer number (6489912).

Almost surely, 2^815721984 is an apocalyptic number.

815721984 is a gapful number since it is divisible by the number (84) 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 815721984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1557578880).

815721984 is an abundant number, since it is smaller than the sum of its proper divisors (2299435776).

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

815721984 is a wasteful number, since it uses less digits than its factorization.

815721984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 42 counting only the distinct ones).

The product of its digits is 161280, while the sum is 45.

The square root of 815721984 is about 28560.8470462625. The cubic root of 815721984 is about 934.3596076241.

The spelling of 815721984 in words is "eight hundred fifteen million, seven hundred twenty-one thousand, nine hundred eighty-four".