21203542 has 4 divisors (see below), whose sum is σ = 31805316. Its totient is φ = 10601770.

The previous prime is 21203513. The next prime is 21203543. The reversal of 21203542 is 24530212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203543) 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 as a sum of consecutive naturals, namely, 5300884 + ... + 5300887.

It is an arithmetic number, because the mean of its divisors is an integer number (7951329).

Almost surely, 2^21203542 is an apocalyptic number.

21203542 is a deficient number, since it is larger than the sum of its proper divisors (10601774).

21203542 is a wasteful number, since it uses less digits than its factorization.

21203542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10601773.

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

The square root of 21203542 is about 4604.7303938450. The cubic root of 21203542 is about 276.7809134461.

Adding to 21203542 its reverse (24530212), we get a palindrome (45733754).

The spelling of 21203542 in words is "twenty-one million, two hundred three thousand, five hundred forty-two".