21542203 has 4 divisors (see below), whose sum is σ = 21743640. Its totient is φ = 21340768.

The previous prime is 21542173. The next prime is 21542231. The reversal of 21542203 is 30224512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21542203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 100558 + ... + 100771.

It is an arithmetic number, because the mean of its divisors is an integer number (5435910).

Almost surely, 2^21542203 is an apocalyptic number.

21542203 is a deficient number, since it is larger than the sum of its proper divisors (201437).

21542203 is a wasteful number, since it uses less digits than its factorization.

21542203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201436.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21542203 is about 4641.3578832062. The cubic root of 21542203 is about 278.2467100687.

Adding to 21542203 its reverse (30224512), we get a palindrome (51766715).

The spelling of 21542203 in words is "twenty-one million, five hundred forty-two thousand, two hundred three".