21053503 has 2 divisors, whose sum is σ = 21053504. Its totient is φ = 21053502.

The previous prime is 21053491. The next prime is 21053521. The reversal of 21053503 is 30535012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21053503 is a prime.

It is a zygodrome in base 4.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21053563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526751 + 10526752.

It is an arithmetic number, because the mean of its divisors is an integer number (10526752).

Almost surely, 2^21053503 is an apocalyptic number.

21053503 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053503 is an equidigital number, since it uses as much as digits as its factorization.

21053503 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 450, while the sum is 19.

The square root of 21053503 is about 4588.4096373362. The cubic root of 21053503 is about 276.1265216672.

Adding to 21053503 its reverse (30535012), we get a palindrome (51588515).

The spelling of 21053503 in words is "twenty-one million, fifty-three thousand, five hundred three".