21684687436 has 12 divisors (see below), whose sum is σ = 37962493240. Its totient is φ = 10838260800.

The previous prime is 21684687383. The next prime is 21684687461. The reversal of 21684687436 is 63478648612.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1008765 + ... + 1030036.

Almost surely, 2^21684687436 is an apocalyptic number.

It is an amenable number.

21684687436 is a deficient number, since it is larger than the sum of its proper divisors (16277805804).

21684687436 is a wasteful number, since it uses less digits than its factorization.

21684687436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2041464 (or 2041462 counting only the distinct ones).

The product of its digits is 9289728, while the sum is 55.

The spelling of 21684687436 in words is "twenty-one billion, six hundred eighty-four million, six hundred eighty-seven thousand, four hundred thirty-six".