21606387718 has 8 divisors (see below), whose sum is σ = 32450765112. Its totient is φ = 10789466016.

The previous prime is 21606387707. The next prime is 21606387721. The reversal of 21606387718 is 81778360612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6861955 + ... + 6865102.

It is an arithmetic number, because the mean of its divisors is an integer number (4056345639).

Almost surely, 2^21606387718 is an apocalyptic number.

21606387718 is a deficient number, since it is larger than the sum of its proper divisors (10844377394).

21606387718 is a wasteful number, since it uses less digits than its factorization.

21606387718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13727846.

The product of its (nonzero) digits is 677376, while the sum is 49.

The spelling of 21606387718 in words is "twenty-one billion, six hundred six million, three hundred eighty-seven thousand, seven hundred eighteen".