21927289 has 4 divisors (see below), whose sum is σ = 21940480. Its totient is φ = 21914100.

The previous prime is 21927281. The next prime is 21927293. The reversal of 21927289 is 98272912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21927289 - 2³ = 21927281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21927281) 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, 3669 + ... + 7570.

It is an arithmetic number, because the mean of its divisors is an integer number (5485120).

Almost surely, 2^21927289 is an apocalyptic number.

It is an amenable number.

21927289 is a deficient number, since it is larger than the sum of its proper divisors (13191).

21927289 is a wasteful number, since it uses less digits than its factorization.

21927289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13190.

The product of its digits is 36288, while the sum is 40.

The square root of 21927289 is about 4682.6583262075. The cubic root of 21927289 is about 279.8948967770.

It can be divided in two parts, 2 and 1927289, that added together give a palindrome (1927291).

The spelling of 21927289 in words is "twenty-one million, nine hundred twenty-seven thousand, two hundred eighty-nine".