21057203 has 4 divisors (see below), whose sum is σ = 22295880. Its totient is φ = 19818528.

The previous prime is 21057199. The next prime is 21057209. The reversal of 21057203 is 30275012.

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

It is a cyclic number.

It is not a de Polignac number, because 21057203 - 2² = 21057199 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21057209) 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, 619313 + ... + 619346.

It is an arithmetic number, because the mean of its divisors is an integer number (5573970).

Almost surely, 2^21057203 is an apocalyptic number.

21057203 is a deficient number, since it is larger than the sum of its proper divisors (1238677).

21057203 is a wasteful number, since it uses less digits than its factorization.

21057203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238676.

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21057203 is about 4588.8128094312. The cubic root of 21057203 is about 276.1426964623.

The spelling of 21057203 in words is "twenty-one million, fifty-seven thousand, two hundred three".