16491221280 has 432 divisors, whose sum is σ = 61658650872. Its totient is φ = 3999744000.

The previous prime is 16491221273. The next prime is 16491221291. The reversal of 16491221280 is 8212219461.

16491221280 is a `hidden beast` number, since 1 + 649 + 1 + 2 + 2 + 1 + 2 + 8 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 16280739216 + 210482064 = 127596^2 + 14508^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 23524930 + ... + 23525630.

Almost surely, 2^16491221280 is an apocalyptic number.

16491221280 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 16491221280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30829325436).

16491221280 is an abundant number, since it is smaller than the sum of its proper divisors (45167429592).

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

16491221280 is a wasteful number, since it uses less digits than its factorization.

16491221280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801 (or 759 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 16491221280 in words is "sixteen billion, four hundred ninety-one million, two hundred twenty-one thousand, two hundred eighty".