21066616065 has 48 divisors (see below), whose sum is σ = 37298520000. Its totient is φ = 10145435520.

The previous prime is 21066616061. The next prime is 21066616093. The reversal of 21066616065 is 56061666012.

It is not a de Polignac number, because 21066616065 - 2² = 21066616061 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21066616061) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 231486 + ... + 309384.

It is an arithmetic number, because the mean of its divisors is an integer number (777052500).

Almost surely, 2^21066616065 is an apocalyptic number.

It is an amenable number.

21066616065 is a deficient number, since it is larger than the sum of its proper divisors (16231903935).

21066616065 is a wasteful number, since it uses less digits than its factorization.

21066616065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78078 (or 78067 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 39.

The spelling of 21066616065 in words is "twenty-one billion, sixty-six million, six hundred sixteen thousand, sixty-five".