21893617 has 4 divisors (see below), whose sum is σ = 21937140. Its totient is φ = 21850096.

The previous prime is 21893609. The next prime is 21893621. The reversal of 21893617 is 71639812.

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 17715681 + 4177936 = 4209^2 + 2044^2 .

It is a cyclic number.

It is not a de Polignac number, because 21893617 - 2³ = 21893609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21893647) 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, 20998 + ... + 22015.

It is an arithmetic number, because the mean of its divisors is an integer number (5484285).

Almost surely, 2^21893617 is an apocalyptic number.

It is an amenable number.

21893617 is a deficient number, since it is larger than the sum of its proper divisors (43523).

21893617 is an equidigital number, since it uses as much as digits as its factorization.

21893617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43522.

The product of its digits is 18144, while the sum is 37.

The square root of 21893617 is about 4679.0615512087. The cubic root of 21893617 is about 279.7515525739.

Adding to 21893617 its product of digits (18144), we get a square (21911761 = 4681²).

The spelling of 21893617 in words is "twenty-one million, eight hundred ninety-three thousand, six hundred seventeen".