21566066541 has 32 divisors (see below), whose sum is σ = 30549657600. Its totient is φ = 13504628544.

The previous prime is 21566066507. The next prime is 21566066549. The reversal of 21566066541 is 14566066512.

It is not a de Polignac number, because 21566066541 - 2¹⁰ = 21566065517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21566066493 and 21566066502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21566066549) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 945135 + ... + 967683.

It is an arithmetic number, because the mean of its divisors is an integer number (954676800).

Almost surely, 2^21566066541 is an apocalyptic number.

It is an amenable number.

21566066541 is a deficient number, since it is larger than the sum of its proper divisors (8983591059).

21566066541 is a wasteful number, since it uses less digits than its factorization.

21566066541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22825.

The product of its (nonzero) digits is 259200, while the sum is 42.

The spelling of 21566066541 in words is "twenty-one billion, five hundred sixty-six million, sixty-six thousand, five hundred forty-one".