21789671 has 4 divisors (see below), whose sum is σ = 22737072. Its totient is φ = 20842272.

The previous prime is 21789661. The next prime is 21789679. The reversal of 21789671 is 17698712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21789671 - 2¹⁰ = 21788647 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 (21789679) 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, 473666 + ... + 473711.

It is an arithmetic number, because the mean of its divisors is an integer number (5684268).

Almost surely, 2^21789671 is an apocalyptic number.

21789671 is a deficient number, since it is larger than the sum of its proper divisors (947401).

21789671 is an equidigital number, since it uses as much as digits as its factorization.

21789671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947400.

The product of its digits is 42336, while the sum is 41.

The square root of 21789671 is about 4667.9407665479. The cubic root of 21789671 is about 279.3081174403.

The spelling of 21789671 in words is "twenty-one million, seven hundred eighty-nine thousand, six hundred seventy-one".