21408959 has 8 divisors (see below), whose sum is σ = 25151952. Its totient is φ = 17965440.

The previous prime is 21408949. The next prime is 21408971. The reversal of 21408959 is 95980412.

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 21408959 - 2⁴ = 21408943 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 (21408949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74714 + ... + 74999.

It is an arithmetic number, because the mean of its divisors is an integer number (3143994).

Almost surely, 2^21408959 is an apocalyptic number.

21408959 is a deficient number, since it is larger than the sum of its proper divisors (3742993).

21408959 is a wasteful number, since it uses less digits than its factorization.

21408959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149737.

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 21408959 is about 4626.9816295291. The cubic root of 21408959 is about 277.6718476740.

The spelling of 21408959 in words is "twenty-one million, four hundred eight thousand, nine hundred fifty-nine".