21940789 has 8 divisors (see below), whose sum is σ = 23674392. Its totient is φ = 20213760.

The previous prime is 21940783. The next prime is 21940799. The reversal of 21940789 is 98704912.

It can be written as a sum of positive squares in 4 ways, for example, as 1311025 + 20629764 = 1145^2 + 4542^2 .

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 21940789 - 2⁵ = 21940757 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 (21940783) 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, 7017 + ... + 9649.

It is an arithmetic number, because the mean of its divisors is an integer number (2959299).

Almost surely, 2^21940789 is an apocalyptic number.

It is an amenable number.

21940789 is a deficient number, since it is larger than the sum of its proper divisors (1733603).

21940789 is a wasteful number, since it uses less digits than its factorization.

21940789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3287.

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

The square root of 21940789 is about 4684.0995933050. The cubic root of 21940789 is about 279.9523260670.

The spelling of 21940789 in words is "twenty-one million, nine hundred forty thousand, seven hundred eighty-nine".