21517246729 has 8 divisors (see below), whose sum is σ = 23480713440. Its totient is φ = 19555005600.

The previous prime is 21517246721. The next prime is 21517246753. The reversal of 21517246729 is 92764271512.

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 21517246729 - 2³ = 21517246721 is a prime.

It is a super-2 number, since 2×21517246729² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21517246721) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 269487 + ... + 340084.

It is an arithmetic number, because the mean of its divisors is an integer number (2935089180).

Almost surely, 2^21517246729 is an apocalyptic number.

It is an amenable number.

21517246729 is a deficient number, since it is larger than the sum of its proper divisors (1963466711).

21517246729 is a wasteful number, since it uses less digits than its factorization.

21517246729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612791.

The product of its digits is 423360, while the sum is 46.

The spelling of 21517246729 in words is "twenty-one billion, five hundred seventeen million, two hundred forty-six thousand, seven hundred twenty-nine".