159249681721 has 9 divisors (see below), whose sum is σ = 172447580781. Its totient is φ = 146994917472.

The previous prime is 159249681691. The next prime is 159249681733. The reversal of 159249681721 is 127186942951.

The square root of 159249681721 is 399061.

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 94010305321 + 65239376400 = 306611^2 + 255420^2 .

It is not a de Polignac number, because 159249681721 - 2¹³ = 159249673529 is a prime.

It is a super-2 number, since 2×159249681721² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (159249681751) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5172445 + ... + 5203141.

It is an arithmetic number, because the mean of its divisors is an integer number (19160842309).

Almost surely, 2^159249681721 is an apocalyptic number.

159249681721 is the 399061-st square number.

159249681721 is the 199531-st centered octagonal number.

It is an amenable number.

159249681721 is a deficient number, since it is larger than the sum of its proper divisors (13197899060).

159249681721 is an frugal number, since it uses more digits than its factorization.

159249681721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61420 (or 30710 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 55.

The spelling of 159249681721 in words is "one hundred fifty-nine billion, two hundred forty-nine million, six hundred eighty-one thousand, seven hundred twenty-one".