21013503 has 12 divisors (see below), whose sum is σ = 32592600. Its totient is φ = 12007632.

The previous prime is 21013501. The next prime is 21013507. The reversal of 21013503 is 30531012.

It is a happy number.

It is not a de Polignac number, because 21013503 - 2¹ = 21013501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71328 + ... + 71621.

It is an arithmetic number, because the mean of its divisors is an integer number (2716050).

Almost surely, 2^21013503 is an apocalyptic number.

21013503 is a deficient number, since it is larger than the sum of its proper divisors (11579097).

21013503 is a wasteful number, since it uses less digits than its factorization.

21013503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142966 (or 142959 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21013503 is about 4584.0487562852. The cubic root of 21013503 is about 275.9515379100.

Adding to 21013503 its reverse (30531012), we get a palindrome (51544515).

The spelling of 21013503 in words is "twenty-one million, thirteen thousand, five hundred three".