21408830 has 16 divisors (see below), whose sum is σ = 38601360. Its totient is φ = 8548992.

The previous prime is 21408823. The next prime is 21408833. The reversal of 21408830 is 3880412.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21408830.

It is a congruent number.

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 (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5942 + ... + 8838.

It is an arithmetic number, because the mean of its divisors is an integer number (2412585).

Almost surely, 2^21408830 is an apocalyptic number.

21408830 is a deficient number, since it is larger than the sum of its proper divisors (17192530).

21408830 is a wasteful number, since it uses less digits than its factorization.

21408830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3643.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21408830 is about 4626.9676895349. The cubic root of 21408830 is about 277.6712899676.

The spelling of 21408830 in words is "twenty-one million, four hundred eight thousand, eight hundred thirty".