21505832766 has 24 divisors (see below), whose sum is σ = 50831968824. Its totient is φ = 6516918960.

The previous prime is 21505832729. The next prime is 21505832773. The reversal of 21505832766 is 66723850512.

21505832766 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 583 + 2 + 7 + 66 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54307461 + ... + 54307856.

It is an arithmetic number, because the mean of its divisors is an integer number (2117998701).

Almost surely, 2^21505832766 is an apocalyptic number.

21505832766 is an abundant number, since it is smaller than the sum of its proper divisors (29326136058).

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

21505832766 is a wasteful number, since it uses less digits than its factorization.

21505832766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108615336 (or 108615333 counting only the distinct ones).

The product of its (nonzero) digits is 604800, while the sum is 45.

The spelling of 21505832766 in words is "twenty-one billion, five hundred five million, eight hundred thirty-two thousand, seven hundred sixty-six".