159551721 has 64 divisors (see below), whose sum is σ = 287180800. Its totient is φ = 85520448.

The previous prime is 159551719. The next prime is 159551729. The reversal of 159551721 is 127155951.

It is not a de Polignac number, because 159551721 - 2¹ = 159551719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (159551729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 563646 + ... + 563928.

It is an arithmetic number, because the mean of its divisors is an integer number (4487200).

Almost surely, 2^159551721 is an apocalyptic number.

It is an amenable number.

159551721 is a deficient number, since it is larger than the sum of its proper divisors (127629079).

159551721 is a wasteful number, since it uses less digits than its factorization.

159551721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475 (or 469 counting only the distinct ones).

The product of its digits is 15750, while the sum is 36.

The square root of 159551721 is about 12631.3784283426. The cubic root of 159551721 is about 542.3760422400.

The spelling of 159551721 in words is "one hundred fifty-nine million, five hundred fifty-one thousand, seven hundred twenty-one".