21253203 has 6 divisors (see below), whose sum is σ = 30699084. Its totient is φ = 14168796.

The previous prime is 21253189. The next prime is 21253217. The reversal of 21253203 is 30235212.

It is an interprime number because it is at equal distance from previous prime (21253189) and next prime (21253217).

It is not a de Polignac number, because 21253203 - 2⁹ = 21252691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21253103) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1180725 + ... + 1180742.

It is an arithmetic number, because the mean of its divisors is an integer number (5116514).

Almost surely, 2^21253203 is an apocalyptic number.

21253203 is a deficient number, since it is larger than the sum of its proper divisors (9445881).

21253203 is a wasteful number, since it uses less digits than its factorization.

21253203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2361473 (or 2361470 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21253203 is about 4610.1196296842. The cubic root of 21253203 is about 276.9968286291.

Adding to 21253203 its reverse (30235212), we get a palindrome (51488415).

Subtracting 21253203 from its reverse (30235212), we obtain a square (8982009 = 2997²).

The spelling of 21253203 in words is "twenty-one million, two hundred fifty-three thousand, two hundred three".