21089385 has 12 divisors (see below), whose sum is σ = 36555012. Its totient is φ = 11247648.

The previous prime is 21089381. The next prime is 21089407. The reversal of 21089385 is 58398012.

It can be written as a sum of positive squares in 2 ways, for example, as 4613904 + 16475481 = 2148^2 + 4059^2 .

It is not a de Polignac number, because 21089385 - 2² = 21089381 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21089381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 234282 + ... + 234371.

It is an arithmetic number, because the mean of its divisors is an integer number (3046251).

Almost surely, 2^21089385 is an apocalyptic number.

It is an amenable number.

21089385 is a deficient number, since it is larger than the sum of its proper divisors (15465627).

21089385 is a wasteful number, since it uses less digits than its factorization.

21089385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 468664 (or 468661 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21089385 is about 4592.3180421221. The cubic root of 21089385 is about 276.2833023603.

The spelling of 21089385 in words is "twenty-one million, eighty-nine thousand, three hundred eighty-five".