21666013027 has 8 divisors (see below), whose sum is σ = 22050327600. Its totient is φ = 21284064000.

The previous prime is 21666012961. The next prime is 21666013037. The reversal of 21666013027 is 72031066612.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21666013027 is a prime.

It is a super-2 number, since 2×21666013027² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21666012983 and 21666013001.

It is not an unprimeable number, because it can be changed into a prime (21666013037) 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, 572902 + ... + 609547.

It is an arithmetic number, because the mean of its divisors is an integer number (2756290950).

Almost surely, 2^21666013027 is an apocalyptic number.

21666013027 is a deficient number, since it is larger than the sum of its proper divisors (384314573).

21666013027 is a wasteful number, since it uses less digits than its factorization.

21666013027 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1182773.

The product of its (nonzero) digits is 18144, while the sum is 34.

Adding to 21666013027 its reverse (72031066612), we get a palindrome (93697079639).

The spelling of 21666013027 in words is "twenty-one billion, six hundred sixty-six million, thirteen thousand, twenty-seven".