21315605503 has 4 divisors (see below), whose sum is σ = 21318184728. Its totient is φ = 21313026280.

The previous prime is 21315605413. The next prime is 21315605527. The reversal of 21315605503 is 30550651312.

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

It is a cyclic number.

It is not a de Polignac number, because 21315605503 - 2¹⁷ = 21315474431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315605593) 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, 1277176 + ... + 1293757.

It is an arithmetic number, because the mean of its divisors is an integer number (5329546182).

Almost surely, 2^21315605503 is an apocalyptic number.

21315605503 is a deficient number, since it is larger than the sum of its proper divisors (2579225).

21315605503 is an equidigital number, since it uses as much as digits as its factorization.

21315605503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2579224.

The product of its (nonzero) digits is 13500, while the sum is 31.

The spelling of 21315605503 in words is "twenty-one billion, three hundred fifteen million, six hundred five thousand, five hundred three".