21103905 has 8 divisors (see below), whose sum is σ = 33766272. Its totient is φ = 11255408.

The previous prime is 21103897. The next prime is 21103933. The reversal of 21103905 is 50930112.

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 21103905 - 2³ = 21103897 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 703449 + ... + 703478.

It is an arithmetic number, because the mean of its divisors is an integer number (4220784).

Almost surely, 2^21103905 is an apocalyptic number.

It is an amenable number.

21103905 is a deficient number, since it is larger than the sum of its proper divisors (12662367).

21103905 is a wasteful number, since it uses less digits than its factorization.

21103905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1406935.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21103905 is about 4593.8986710636. The cubic root of 21103905 is about 276.3466946504.

The spelling of 21103905 in words is "twenty-one million, one hundred three thousand, nine hundred five".