21968893 has 4 divisors (see below), whose sum is σ = 21978940. Its totient is φ = 21958848.

The previous prime is 21968867. The next prime is 21968899. The reversal of 21968893 is 39886912.

It is the 1914-th star number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16337764 + 5631129 = 4042^2 + 2373^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21968893 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 (21968899) 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, 198 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (5494735).

Almost surely, 2^21968893 is an apocalyptic number.

It is an amenable number.

21968893 is a deficient number, since it is larger than the sum of its proper divisors (10047).

21968893 is an equidigital number, since it uses as much as digits as its factorization.

21968893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10046.

The product of its digits is 186624, while the sum is 46.

The square root of 21968893 is about 4687.0985694777. The cubic root of 21968893 is about 280.0718055636.

The spelling of 21968893 in words is "twenty-one million, nine hundred sixty-eight thousand, eight hundred ninety-three".