21408835 has 12 divisors (see below), whose sum is σ = 29885328. Its totient is φ = 14680176.

The previous prime is 21408833. The next prime is 21408841. The reversal of 21408835 is 53880412.

It is not a de Polignac number, because 21408835 - 2¹ = 21408833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21408797 and 21408806.

It is not an unprimeable number, because it can be changed into a prime (21408833) 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, 43447 + ... + 43936.

It is an arithmetic number, because the mean of its divisors is an integer number (2490444).

Almost surely, 2^21408835 is an apocalyptic number.

21408835 is a deficient number, since it is larger than the sum of its proper divisors (8476493).

21408835 is an equidigital number, since it uses as much as digits as its factorization.

21408835 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87402 (or 87395 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 31.

The square root of 21408835 is about 4626.9682298455. The cubic root of 21408835 is about 277.6713115842.

The spelling of 21408835 in words is "twenty-one million, four hundred eight thousand, eight hundred thirty-five".