21315403 has 4 divisors (see below), whose sum is σ = 21478248. Its totient is φ = 21152560.

The previous prime is 21315391. The next prime is 21315421. The reversal of 21315403 is 30451312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21315403 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21315443) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81226 + ... + 81487.

It is an arithmetic number, because the mean of its divisors is an integer number (5369562).

Almost surely, 2^21315403 is an apocalyptic number.

21315403 is a deficient number, since it is larger than the sum of its proper divisors (162845).

21315403 is a wasteful number, since it uses less digits than its factorization.

21315403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162844.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21315403 is about 4616.8607299766. The cubic root of 21315403 is about 277.2667867189.

Adding to 21315403 its reverse (30451312), we get a palindrome (51766715).

The spelling of 21315403 in words is "twenty-one million, three hundred fifteen thousand, four hundred three".