21989789 has 8 divisors (see below), whose sum is σ = 23332608. Its totient is φ = 20652480.

The previous prime is 21989777. The next prime is 21989797. The reversal of 21989789 is 98798912.

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 21989789 - 2¹² = 21985693 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21989789.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989089) 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, 9254 + ... + 11384.

It is an arithmetic number, because the mean of its divisors is an integer number (2916576).

Almost surely, 2^21989789 is an apocalyptic number.

It is an amenable number.

21989789 is a deficient number, since it is larger than the sum of its proper divisors (1342819).

21989789 is a wasteful number, since it uses less digits than its factorization.

21989789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2755.

The product of its digits is 653184, while the sum is 53.

The square root of 21989789 is about 4689.3271372341. The cubic root of 21989789 is about 280.1605754120.

The spelling of 21989789 in words is "twenty-one million, nine hundred eighty-nine thousand, seven hundred eighty-nine".