21526663680 has 200 divisors, whose sum is σ = 77102450172. Its totient is φ = 5740388352.

The previous prime is 21526663673. The next prime is 21526663693. The reversal of 21526663680 is 8636662512.

It can be written as a sum of positive squares in 2 ways, for example, as 19390005504 + 2136658176 = 139248^2 + 46224^2 .

It is a super-2 number, since 2×21526663680² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 155454 + ... + 259266.

Almost surely, 2^21526663680 is an apocalyptic number.

21526663680 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 21526663680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38551225086).

21526663680 is an abundant number, since it is smaller than the sum of its proper divisors (55575786492).

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

21526663680 is an equidigital number, since it uses as much as digits as its factorization.

21526663680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103848 (or 103823 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 21526663680 in words is "twenty-one billion, five hundred twenty-six million, six hundred sixty-three thousand, six hundred eighty".