21257203 has 16 divisors (see below), whose sum is σ = 24651360. Its totient is φ = 18144000.

The previous prime is 21257189. The next prime is 21257209. The reversal of 21257203 is 30275212.

It is a cyclic number.

It is not a de Polignac number, because 21257203 - 2⁹ = 21256691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21257209) 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, 10903 + ... + 12703.

It is an arithmetic number, because the mean of its divisors is an integer number (1540710).

Almost surely, 2^21257203 is an apocalyptic number.

21257203 is a deficient number, since it is larger than the sum of its proper divisors (3394157).

21257203 is a wasteful number, since it uses less digits than its factorization.

21257203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21257203 is about 4610.5534374953. The cubic root of 21257203 is about 277.0142051129.

Subtracting 21257203 from its reverse (30275212), we obtain a square (9018009 = 3003²).

The spelling of 21257203 in words is "twenty-one million, two hundred fifty-seven thousand, two hundred three".