21500487 has 12 divisors (see below), whose sum is σ = 31566184. Its totient is φ = 14098320.

The previous prime is 21500483. The next prime is 21500489. The reversal of 21500487 is 78400512.

It is not a de Polignac number, because 21500487 - 2² = 21500483 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21500487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21500483) 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, 19033 + ... + 20130.

Almost surely, 2^21500487 is an apocalyptic number.

21500487 is a deficient number, since it is larger than the sum of its proper divisors (10065697).

21500487 is a wasteful number, since it uses less digits than its factorization.

21500487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39230 (or 39227 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21500487 is about 4636.8617620110. The cubic root of 21500487 is about 278.0669878079.

Adding to 21500487 its reverse (78400512), we get a palindrome (99900999).

The spelling of 21500487 in words is "twenty-one million, five hundred thousand, four hundred eighty-seven".