21030503 has 8 divisors (see below), whose sum is σ = 22689408. Its totient is φ = 19377504.

The previous prime is 21030469. The next prime is 21030551. The reversal of 21030503 is 30503012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21030503 - 2¹⁶ = 20964967 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8426 + ... + 10632.

It is an arithmetic number, because the mean of its divisors is an integer number (2836176).

Almost surely, 2^21030503 is an apocalyptic number.

21030503 is a deficient number, since it is larger than the sum of its proper divisors (1658905).

21030503 is a wasteful number, since it uses less digits than its factorization.

21030503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2953.

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21030503 is about 4585.9026374314. The cubic root of 21030503 is about 276.0259331160.

Adding to 21030503 its reverse (30503012), we get a palindrome (51533515).

The spelling of 21030503 in words is "twenty-one million, thirty thousand, five hundred three".