21053003 has 4 divisors (see below), whose sum is σ = 21065088. Its totient is φ = 21040920.

The previous prime is 21052979. The next prime is 21053009. The reversal of 21053003 is 30035012.

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 21053003 - 2¹⁴ = 21036619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21053009) 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, 2876 + ... + 7097.

It is an arithmetic number, because the mean of its divisors is an integer number (5266272).

Almost surely, 2^21053003 is an apocalyptic number.

21053003 is a deficient number, since it is larger than the sum of its proper divisors (12085).

21053003 is an equidigital number, since it uses as much as digits as its factorization.

21053003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12084.

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21053003 is about 4588.3551519036. The cubic root of 21053003 is about 276.1243357388.

Adding to 21053003 its reverse (30035012), we get a palindrome (51088015).

Subtracting 21053003 from its reverse (30035012), we obtain a square (8982009 = 2997²).

The spelling of 21053003 in words is "twenty-one million, fifty-three thousand, three".