21406105 has 8 divisors (see below), whose sum is σ = 29356992. Its totient is φ = 14678448.

The previous prime is 21406087. The next prime is 21406109. The reversal of 21406105 is 50160412.

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 21406105 - 2¹⁵ = 21373337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21406109) 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 7 ways as a sum of consecutive naturals, for example, 305767 + ... + 305836.

It is an arithmetic number, because the mean of its divisors is an integer number (3669624).

Almost surely, 2^21406105 is an apocalyptic number.

It is an amenable number.

21406105 is a deficient number, since it is larger than the sum of its proper divisors (7950887).

21406105 is an equidigital number, since it uses as much as digits as its factorization.

21406105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611615.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21406105 is about 4626.6732108503. The cubic root of 21406105 is about 277.6595084368.

Adding to 21406105 its reverse (50160412), we get a palindrome (71566517).

The spelling of 21406105 in words is "twenty-one million, four hundred six thousand, one hundred five".