17945549521 has 9 divisors (see below), whose sum is σ = 18126446961. Its totient is φ = 17766443664.

The previous prime is 17945549513. The next prime is 17945549551. The reversal of 17945549521 is 12594554971.

The square root of 17945549521 is 133961.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 10549549521 + 7396000000 = 102711^2 + 86000^2 .

It is not a de Polignac number, because 17945549521 - 2³ = 17945549513 is a prime.

It is a super-2 number, since 2×17945549521² (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 (17945549551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 14601135 + ... + 14602363.

Almost surely, 2^17945549521 is an apocalyptic number.

17945549521 is the 133961-st square number.

17945549521 is the 66981-st centered octagonal number.

It is an amenable number.

17945549521 is a deficient number, since it is larger than the sum of its proper divisors (180897440).

17945549521 is an frugal number, since it uses more digits than its factorization.

17945549521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2676 (or 1338 counting only the distinct ones).

The product of its digits is 2268000, while the sum is 52.

The spelling of 17945549521 in words is "seventeen billion, nine hundred forty-five million, five hundred forty-nine thousand, five hundred twenty-one".