16821721380 has 48 divisors (see below), whose sum is σ = 47117214144. Its totient is φ = 4484231040.

The previous prime is 16821721379. The next prime is 16821721381. The reversal of 16821721380 is 8312712861.

16821721380 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (16821721379) and next prime (16821721381).

It is not an unprimeable number, because it can be changed into a prime (16821721381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 130470 + ... + 225090.

It is an arithmetic number, because the mean of its divisors is an integer number (981608628).

Almost surely, 2^16821721380 is an apocalyptic number.

16821721380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16821721380 is an abundant number, since it is smaller than the sum of its proper divisors (30295492764).

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

16821721380 is a wasteful number, since it uses less digits than its factorization.

16821721380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97596 (or 97594 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 39.

The spelling of 16821721380 in words is "sixteen billion, eight hundred twenty-one million, seven hundred twenty-one thousand, three hundred eighty".