21487736 has 8 divisors (see below), whose sum is σ = 40289520. Its totient is φ = 10743864.

The previous prime is 21487717. The next prime is 21487751. The reversal of 21487736 is 63778412.

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 21487736.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1342976 + ... + 1342991.

It is an arithmetic number, because the mean of its divisors is an integer number (5036190).

Almost surely, 2^21487736 is an apocalyptic number.

It is an amenable number.

21487736 is a deficient number, since it is larger than the sum of its proper divisors (18801784).

21487736 is a wasteful number, since it uses less digits than its factorization.

21487736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2685973 (or 2685969 counting only the distinct ones).

The product of its digits is 56448, while the sum is 38.

The square root of 21487736 is about 4635.4865979744. The cubic root of 21487736 is about 278.0120071414.

The spelling of 21487736 in words is "twenty-one million, four hundred eighty-seven thousand, seven hundred thirty-six".