21727689 has 8 divisors (see below), whose sum is σ = 28992480. Its totient is φ = 14474016.

The previous prime is 21727687. The next prime is 21727703. The reversal of 21727689 is 98672712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21727689 - 2¹ = 21727687 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21727689.

It is not an unprimeable number, because it can be changed into a prime (21727681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4534 + ... + 8000.

It is an arithmetic number, because the mean of its divisors is an integer number (3624060).

Almost surely, 2^21727689 is an apocalyptic number.

It is an amenable number.

21727689 is a deficient number, since it is larger than the sum of its proper divisors (7264791).

21727689 is a wasteful number, since it uses less digits than its factorization.

21727689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5559.

The product of its digits is 84672, while the sum is 42.

The square root of 21727689 is about 4661.2969225313. The cubic root of 21727689 is about 279.0430298093.

The spelling of 21727689 in words is "twenty-one million, seven hundred twenty-seven thousand, six hundred eighty-nine".