21164903 has 4 divisors (see below), whose sum is σ = 21174168. Its totient is φ = 21155640.

The previous prime is 21164863. The next prime is 21164929. The reversal of 21164903 is 30946112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21164903 - 2⁶ = 21164839 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 (21164953) 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, 1508 + ... + 6678.

It is an arithmetic number, because the mean of its divisors is an integer number (5293542).

Almost surely, 2^21164903 is an apocalyptic number.

21164903 is a deficient number, since it is larger than the sum of its proper divisors (9265).

21164903 is an equidigital number, since it uses as much as digits as its factorization.

21164903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9264.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 21164903 is about 4600.5329039145. The cubic root of 21164903 is about 276.6126861992.

The spelling of 21164903 in words is "twenty-one million, one hundred sixty-four thousand, nine hundred three".