16515728645 has 18 divisors (see below), whose sum is σ = 21465529974. Its totient is φ = 12193471680.

The previous prime is 16515728639. The next prime is 16515728653. The reversal of 16515728645 is 54682751561.

It can be written as a sum of positive squares in 9 ways, for example, as 3701262244 + 12814466401 = 60838^2 + 113201^2 .

It is not a de Polignac number, because 16515728645 - 2⁸ = 16515728389 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16515728593 and 16515728602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3733535 + ... + 3737955.

It is an arithmetic number, because the mean of its divisors is an integer number (1192529443).

Almost surely, 2^16515728645 is an apocalyptic number.

It is an amenable number.

16515728645 is a deficient number, since it is larger than the sum of its proper divisors (4949801329).

16515728645 is an frugal number, since it uses more digits than its factorization.

16515728645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8873 (or 4439 counting only the distinct ones).

The product of its digits is 2016000, while the sum is 50.

The spelling of 16515728645 in words is "sixteen billion, five hundred fifteen million, seven hundred twenty-eight thousand, six hundred forty-five".