21686729413 has 16 divisors (see below), whose sum is σ = 22224758400. Its totient is φ = 21156791040.

The previous prime is 21686729411. The next prime is 21686729419. The reversal of 21686729413 is 31492768612.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21686729413 - 2¹ = 21686729411 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 (21686729411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2571718 + ... + 2580136.

It is an arithmetic number, because the mean of its divisors is an integer number (1389047400).

Almost surely, 2^21686729413 is an apocalyptic number.

It is an amenable number.

21686729413 is a deficient number, since it is larger than the sum of its proper divisors (538028987).

21686729413 is a wasteful number, since it uses less digits than its factorization.

21686729413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8892.

The product of its digits is 870912, while the sum is 49.

The spelling of 21686729413 in words is "twenty-one billion, six hundred eighty-six million, seven hundred twenty-nine thousand, four hundred thirteen".