21665232201 has 32 divisors (see below), whose sum is σ = 30970240000. Its totient is φ = 13430940480.

The previous prime is 21665232161. The next prime is 21665232221. The reversal of 21665232201 is 10223256612.

It is not a de Polignac number, because 21665232201 - 2¹⁵ = 21665199433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21665232221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1728780 + ... + 1741266.

It is an arithmetic number, because the mean of its divisors is an integer number (967820000).

Almost surely, 2^21665232201 is an apocalyptic number.

It is an amenable number.

21665232201 is a deficient number, since it is larger than the sum of its proper divisors (9305007799).

21665232201 is a wasteful number, since it uses less digits than its factorization.

21665232201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13069.

The product of its (nonzero) digits is 8640, while the sum is 30.

Adding to 21665232201 its reverse (10223256612), we get a palindrome (31888488813).

The spelling of 21665232201 in words is "twenty-one billion, six hundred sixty-five million, two hundred thirty-two thousand, two hundred one".