21526581680 has 40 divisors (see below), whose sum is σ = 51775146000. Its totient is φ = 8313713408.

The previous prime is 21526581679. The next prime is 21526581701. The reversal of 21526581680 is 8618562512.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 4637030 + ... + 4641669.

It is an arithmetic number, because the mean of its divisors is an integer number (1294378650).

Almost surely, 2^21526581680 is an apocalyptic number.

21526581680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21526581680 is an abundant number, since it is smaller than the sum of its proper divisors (30248564320).

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

21526581680 is a wasteful number, since it uses less digits than its factorization.

21526581680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9278741 (or 9278735 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 44.

The spelling of 21526581680 in words is "twenty-one billion, five hundred twenty-six million, five hundred eighty-one thousand, six hundred eighty".