21052503 has 24 divisors (see below), whose sum is σ = 31930496. Its totient is φ = 13348800.

The previous prime is 21052489. The next prime is 21052547. The reversal of 21052503 is 30525012.

It is a happy number.

It is not a de Polignac number, because 21052503 - 2⁹ = 21051991 is a prime.

It is a super-4 number, since 4×21052503⁴ (a number of 30 digits) contains 4444 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052553) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16401 + ... + 17637.

Almost surely, 2^21052503 is an apocalyptic number.

21052503 is a deficient number, since it is larger than the sum of its proper divisors (10877993).

21052503 is a wasteful number, since it uses less digits than its factorization.

21052503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1335 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21052503 is about 4588.3006658239. The cubic root of 21052503 is about 276.1221497757.

Adding to 21052503 its reverse (30525012), we get a palindrome (51577515).

The spelling of 21052503 in words is "twenty-one million, fifty-two thousand, five hundred three".