21026959 has 4 divisors (see below), whose sum is σ = 21705280. Its totient is φ = 20348640.

The previous prime is 21026953. The next prime is 21026983. The reversal of 21026959 is 95962012.

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

It is a cyclic number.

It is not a de Polignac number, because 21026959 - 2¹¹ = 21024911 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 (21026953) 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 3 ways as a sum of consecutive naturals, for example, 339114 + ... + 339175.

It is an arithmetic number, because the mean of its divisors is an integer number (5426320).

Almost surely, 2^21026959 is an apocalyptic number.

21026959 is a deficient number, since it is larger than the sum of its proper divisors (678321).

21026959 is an equidigital number, since it uses as much as digits as its factorization.

21026959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678320.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 21026959 is about 4585.5162195766. The cubic root of 21026959 is about 276.0104272123.

The spelling of 21026959 in words is "twenty-one million, twenty-six thousand, nine hundred fifty-nine".