981721440 has 432 divisors, whose sum is σ = 4079248992. Its totient is φ = 210567168.

The previous prime is 981721379. The next prime is 981721441. The reversal of 981721440 is 44127189.

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 = 981721395 and 981721404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981721441) 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 71 ways as a sum of consecutive naturals, for example, 2912952 + ... + 2913288.

It is an arithmetic number, because the mean of its divisors is an integer number (9442706).

Almost surely, 2^981721440 is an apocalyptic number.

981721440 is a gapful number since it is divisible by the number (90) 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 981721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2039624496).

981721440 is an abundant number, since it is smaller than the sum of its proper divisors (3097527552).

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

981721440 is a wasteful number, since it uses less digits than its factorization.

981721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399 (or 371 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 981721440 is about 31332.4343133437. The cubic root of 981721440 is about 993.8696421752.

The spelling of 981721440 in words is "nine hundred eighty-one million, seven hundred twenty-one thousand, four hundred forty".