21971689 has 8 divisors (see below), whose sum is σ = 22276800. Its totient is φ = 21668976.

The previous prime is 21971687. The next prime is 21971707. The reversal of 21971689 is 98617912.

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

It is a cyclic number.

It is not a de Polignac number, because 21971689 - 2¹ = 21971687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21971681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24442 + ... + 25324.

It is an arithmetic number, because the mean of its divisors is an integer number (2784600).

Almost surely, 2^21971689 is an apocalyptic number.

It is an amenable number.

21971689 is a deficient number, since it is larger than the sum of its proper divisors (305111).

21971689 is a wasteful number, since it uses less digits than its factorization.

21971689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1199.

The product of its digits is 54432, while the sum is 43.

The square root of 21971689 is about 4687.3968255312. The cubic root of 21971689 is about 280.0836867198.

The spelling of 21971689 in words is "twenty-one million, nine hundred seventy-one thousand, six hundred eighty-nine".