21666232201 has 4 divisors (see below), whose sum is σ = 21693417732. Its totient is φ = 21639046672.

The previous prime is 21666232187. The next prime is 21666232279. The reversal of 21666232201 is 10223266612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11172278601 + 10493953600 = 105699^2 + 102440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21666232201 - 2⁵ = 21666232169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21666262201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13591570 + ... + 13593163.

It is an arithmetic number, because the mean of its divisors is an integer number (5423354433).

Almost surely, 2^21666232201 is an apocalyptic number.

It is an amenable number.

21666232201 is a deficient number, since it is larger than the sum of its proper divisors (27185531).

21666232201 is an equidigital number, since it uses as much as digits as its factorization.

21666232201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27185530.

The product of its (nonzero) digits is 10368, while the sum is 31.

Adding to 21666232201 its reverse (10223266612), we get a palindrome (31889498813).

The spelling of 21666232201 in words is "twenty-one billion, six hundred sixty-six million, two hundred thirty-two thousand, two hundred one".