21888169 has 4 divisors (see below), whose sum is σ = 21912660. Its totient is φ = 21863680.

The previous prime is 21888151. The next prime is 21888173. The reversal of 21888169 is 96188812.

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 1996569 + 19891600 = 1413^2 + 4460^2 .

It is a cyclic number.

It is not a de Polignac number, because 21888169 - 2¹⁵ = 21855401 is a prime.

It is a super-2 number, since 2×21888169² = 958183884345122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21888109) 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, 10852 + ... + 12709.

It is an arithmetic number, because the mean of its divisors is an integer number (5478165).

Almost surely, 2^21888169 is an apocalyptic number.

It is an amenable number.

21888169 is a deficient number, since it is larger than the sum of its proper divisors (24491).

21888169 is an equidigital number, since it uses as much as digits as its factorization.

21888169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24490.

The product of its digits is 55296, while the sum is 43.

The square root of 21888169 is about 4678.4793469673. The cubic root of 21888169 is about 279.7283462228.

The spelling of 21888169 in words is "twenty-one million, eight hundred eighty-eight thousand, one hundred sixty-nine".