21280444416 has 1040 divisors, whose sum is σ = 85631990400. Its totient is φ = 5202247680.

The previous prime is 21280444373. The next prime is 21280444447. The reversal of 21280444416 is 61444408212.

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

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 79 ways as a sum of consecutive naturals, for example, 1251790840 + ... + 1251790856.

Almost surely, 2^21280444416 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21280444416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42815995200).

21280444416 is an abundant number, since it is smaller than the sum of its proper divisors (64351545984).

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

21280444416 is an equidigital number, since it uses as much as digits as its factorization.

21280444416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 36.

The spelling of 21280444416 in words is "twenty-one billion, two hundred eighty million, four hundred forty-four thousand, four hundred sixteen".