16655521721 has 8 divisors (see below), whose sum is σ = 16780714944. Its totient is φ = 16530631920.

The previous prime is 16655521651. The next prime is 16655521739. The reversal of 16655521721 is 12712555661.

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 16655521721 - 2¹⁰ = 16655520697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16655521021) 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, 34946 + ... + 185828.

It is an arithmetic number, because the mean of its divisors is an integer number (2097589368).

Almost surely, 2^16655521721 is an apocalyptic number.

It is an amenable number.

16655521721 is a deficient number, since it is larger than the sum of its proper divisors (125193223).

16655521721 is a wasteful number, since it uses less digits than its factorization.

16655521721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151711.

The product of its digits is 126000, while the sum is 41.

The spelling of 16655521721 in words is "sixteen billion, six hundred fifty-five million, five hundred twenty-one thousand, seven hundred twenty-one".