16721555645 has 8 divisors (see below), whose sum is σ = 20126490720. Its totient is φ = 13336828560.

The previous prime is 16721555593. The next prime is 16721555659. The reversal of 16721555645 is 54655512761.

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

It is not a de Polignac number, because 16721555645 - 2⁶ = 16721555581 is a prime.

It is a super-2 number, since 2×16721555645² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16721555645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5050175 + ... + 5053484.

It is an arithmetic number, because the mean of its divisors is an integer number (2515811340).

Almost surely, 2^16721555645 is an apocalyptic number.

It is an amenable number.

16721555645 is a deficient number, since it is larger than the sum of its proper divisors (3404935075).

16721555645 is a wasteful number, since it uses less digits than its factorization.

16721555645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10103995.

The product of its digits is 1260000, while the sum is 47.

The spelling of 16721555645 in words is "sixteen billion, seven hundred twenty-one million, five hundred fifty-five thousand, six hundred forty-five".