21608840729 has 8 divisors (see below), whose sum is σ = 24707025408. Its totient is φ = 18513457920.

The previous prime is 21608840723. The next prime is 21608840761. The reversal of 21608840729 is 92704880612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21608840729 - 2¹² = 21608836633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21608840723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 683912 + ... + 714809.

It is an arithmetic number, because the mean of its divisors is an integer number (3088378176).

Almost surely, 2^21608840729 is an apocalyptic number.

It is an amenable number.

21608840729 is a deficient number, since it is larger than the sum of its proper divisors (3098184679).

21608840729 is a wasteful number, since it uses less digits than its factorization.

21608840729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1400935.

The product of its (nonzero) digits is 387072, while the sum is 47.

The spelling of 21608840729 in words is "twenty-one billion, six hundred eight million, eight hundred forty thousand, seven hundred twenty-nine".