21666065021 has 8 divisors (see below), whose sum is σ = 23937954624. Its totient is φ = 19504999360.

The previous prime is 21666064997. The next prime is 21666065033. The reversal of 21666065021 is 12056066612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21666065021 - 2²² = 21661870717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666065081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27705575 + ... + 27706356.

It is an arithmetic number, because the mean of its divisors is an integer number (2992244328).

Almost surely, 2^21666065021 is an apocalyptic number.

It is an amenable number.

21666065021 is a deficient number, since it is larger than the sum of its proper divisors (2271889603).

21666065021 is a wasteful number, since it uses less digits than its factorization.

21666065021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55411971.

The product of its (nonzero) digits is 25920, while the sum is 35.

The spelling of 21666065021 in words is "twenty-one billion, six hundred sixty-six million, sixty-five thousand, twenty-one".