21490203 has 16 divisors (see below), whose sum is σ = 32935680. Its totient is φ = 12209376.

The previous prime is 21490199. The next prime is 21490213. The reversal of 21490203 is 30209412.

It is not a de Polignac number, because 21490203 - 2² = 21490199 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21490203.

It is not an unprimeable number, because it can be changed into a prime (21490213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 901 + ... + 6617.

It is an arithmetic number, because the mean of its divisors is an integer number (2058480).

Almost surely, 2^21490203 is an apocalyptic number.

21490203 is a deficient number, since it is larger than the sum of its proper divisors (11445477).

21490203 is a wasteful number, since it uses less digits than its factorization.

21490203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5906.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21490203 is about 4635.7526896934. The cubic root of 21490203 is about 278.0226462238.

Adding to 21490203 its reverse (30209412), we get a palindrome (51699615).

The spelling of 21490203 in words is "twenty-one million, four hundred ninety thousand, two hundred three".