21651866227 has 4 divisors (see below), whose sum is σ = 21652224376. Its totient is φ = 21651508080.

The previous prime is 21651866219. The next prime is 21651866237. The reversal of 21651866227 is 72266815612.

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

It is a cyclic number.

It is not a de Polignac number, because 21651866227 - 2³ = 21651866219 is a prime.

It is a super-2 number, since 2×21651866227² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21651866237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63549 + ... + 217582.

It is an arithmetic number, because the mean of its divisors is an integer number (5413056094).

Almost surely, 2^21651866227 is an apocalyptic number.

21651866227 is a deficient number, since it is larger than the sum of its proper divisors (358149).

21651866227 is an equidigital number, since it uses as much as digits as its factorization.

21651866227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358148.

The product of its digits is 483840, while the sum is 46.

The spelling of 21651866227 in words is "twenty-one billion, six hundred fifty-one million, eight hundred sixty-six thousand, two hundred twenty-seven".