21005089 has 8 divisors (see below), whose sum is σ = 25269440. Its totient is φ = 17056656.

The previous prime is 21005087. The next prime is 21005111. The reversal of 21005089 is 98050012.

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 21005089 - 2¹ = 21005087 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21005087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78834 + ... + 79099.

It is an arithmetic number, because the mean of its divisors is an integer number (3158680).

Almost surely, 2^21005089 is an apocalyptic number.

It is an amenable number.

21005089 is a deficient number, since it is larger than the sum of its proper divisors (4264351).

21005089 is a wasteful number, since it uses less digits than its factorization.

21005089 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157959.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 21005089 is about 4583.1309167424. The cubic root of 21005089 is about 275.9147018145.

The spelling of 21005089 in words is "twenty-one million, five thousand, eighty-nine".