21521203 has 8 divisors (see below), whose sum is σ = 23800176. Its totient is φ = 19296000.

The previous prime is 21521183. The next prime is 21521249. The reversal of 21521203 is 30212512.

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 21521203 - 2²¹ = 19424051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21521263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12598 + ... + 14203.

It is an arithmetic number, because the mean of its divisors is an integer number (2975022).

Almost surely, 2^21521203 is an apocalyptic number.

21521203 is a deficient number, since it is larger than the sum of its proper divisors (2278973).

21521203 is a wasteful number, since it uses less digits than its factorization.

21521203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26885.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21521203 is about 4639.0950626173. The cubic root of 21521203 is about 278.1562661984.

Adding to 21521203 its reverse (30212512), we get a palindrome (51733715).

The spelling of 21521203 in words is "twenty-one million, five hundred twenty-one thousand, two hundred three".