21106903 has 4 divisors (see below), whose sum is σ = 21121560. Its totient is φ = 21092248.

The previous prime is 21106873. The next prime is 21106907. The reversal of 21106903 is 30960112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21106903 - 2⁵ = 21106871 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 (21106907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4900 + ... + 8137.

It is an arithmetic number, because the mean of its divisors is an integer number (5280390).

Almost surely, 2^21106903 is an apocalyptic number.

21106903 is a deficient number, since it is larger than the sum of its proper divisors (14657).

21106903 is a wasteful number, since it uses less digits than its factorization.

21106903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14656.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 21106903 is about 4594.2249618407. The cubic root of 21106903 is about 276.3597798774.

The spelling of 21106903 in words is "twenty-one million, one hundred six thousand, nine hundred three".