21028959 has 12 divisors (see below), whose sum is σ = 34714576. Its totient is φ = 12016512.

The previous prime is 21028939. The next prime is 21028979. The reversal of 21028959 is 95982012.

It is an interprime number because it is at equal distance from previous prime (21028939) and next prime (21028979).

It is not a de Polignac number, because 21028959 - 2¹¹ = 21026911 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 (21028919) 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, 166834 + ... + 166959.

Almost surely, 2^21028959 is an apocalyptic number.

21028959 is a deficient number, since it is larger than the sum of its proper divisors (13685617).

21028959 is a wasteful number, since it uses less digits than its factorization.

21028959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333806 (or 333803 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 21028959 is about 4585.7342923462. The cubic root of 21028959 is about 276.0191779364.

The spelling of 21028959 in words is "twenty-one million, twenty-eight thousand, nine hundred fifty-nine".