21566645011 has 2 divisors, whose sum is σ = 21566645012. Its totient is φ = 21566645010.

The previous prime is 21566645003. The next prime is 21566645017. The reversal of 21566645011 is 11054666512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21566645011 - 2³ = 21566645003 is a prime.

It is not a weakly prime, because it can be changed into another prime (21566645017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10783322505 + 10783322506.

It is an arithmetic number, because the mean of its divisors is an integer number (10783322506).

Almost surely, 2^21566645011 is an apocalyptic number.

21566645011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21566645011 is an equidigital number, since it uses as much as digits as its factorization.

21566645011 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21566645011 in words is "twenty-one billion, five hundred sixty-six million, six hundred forty-five thousand, eleven".