21089439 has 12 divisors (see below), whose sum is σ = 34814416. Its totient is φ = 12051072.

The previous prime is 21089437. The next prime is 21089473. The reversal of 21089439 is 93498012.

21089439 is a `hidden beast` number, since 210 + 8 + 9 + 439 = 666.

It is not a de Polignac number, because 21089439 - 2¹ = 21089437 is a prime.

It is a super-3 number, since 3×21089439³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089437) 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 11 ways as a sum of consecutive naturals, for example, 167314 + ... + 167439.

Almost surely, 2^21089439 is an apocalyptic number.

21089439 is a deficient number, since it is larger than the sum of its proper divisors (13724977).

21089439 is a wasteful number, since it uses less digits than its factorization.

21089439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334766 (or 334763 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 21089439 is about 4592.3239215021. The cubic root of 21089439 is about 276.2835381706.

It can be divided in two parts, 21089 and 439, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 21089439 in words is "twenty-one million, eighty-nine thousand, four hundred thirty-nine".