21165306223 has 4 divisors (see below), whose sum is σ = 21166083000. Its totient is φ = 21164529448.

The previous prime is 21165306191. The next prime is 21165306233. The reversal of 21165306223 is 32260356112.

It is a happy number.

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 21165306223 - 2⁵ = 21165306191 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 (21165306233) 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, 345973 + ... + 402526.

It is an arithmetic number, because the mean of its divisors is an integer number (5291520750).

Almost surely, 2^21165306223 is an apocalyptic number.

21165306223 is a deficient number, since it is larger than the sum of its proper divisors (776777).

21165306223 is an equidigital number, since it uses as much as digits as its factorization.

21165306223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 776776.

The product of its (nonzero) digits is 12960, while the sum is 31.

The spelling of 21165306223 in words is "twenty-one billion, one hundred sixty-five million, three hundred six thousand, two hundred twenty-three".