21802789 has 4 divisors (see below), whose sum is σ = 23085324. Its totient is φ = 20520256.

The previous prime is 21802777. The next prime is 21802793. The reversal of 21802789 is 98720812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19210689 + 2592100 = 4383^2 + 1610^2 .

It is a cyclic number.

It is not a de Polignac number, because 21802789 - 2⁵ = 21802757 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 (21802189) 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 3 ways as a sum of consecutive naturals, for example, 641242 + ... + 641275.

It is an arithmetic number, because the mean of its divisors is an integer number (5771331).

Almost surely, 2^21802789 is an apocalyptic number.

It is an amenable number.

21802789 is a deficient number, since it is larger than the sum of its proper divisors (1282535).

21802789 is a wasteful number, since it uses less digits than its factorization.

21802789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1282534.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 21802789 is about 4669.3456715047. The cubic root of 21802789 is about 279.3641566658.

The spelling of 21802789 in words is "twenty-one million, eight hundred two thousand, seven hundred eighty-nine".