21756641280 has 304 divisors, whose sum is σ = 76101306624. Its totient is φ = 5263851520.

The previous prime is 21756641279. The next prime is 21756641303. The reversal of 21756641280 is 8214665712.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43253509 + ... + 43254011.

Almost surely, 2^21756641280 is an apocalyptic number.

21756641280 is a gapful number since it is divisible by the number (20) 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 21756641280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38050653312).

21756641280 is an abundant number, since it is smaller than the sum of its proper divisors (54344665344).

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

21756641280 is an frugal number, since it uses more digits than its factorization.

21756641280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 558 (or 524 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 42.

The spelling of 21756641280 in words is "twenty-one billion, seven hundred fifty-six million, six hundred forty-one thousand, two hundred eighty".