161997759 has 64 divisors (see below), whose sum is σ = 303943680. Its totient is φ = 82827360.

The previous prime is 161997757. The next prime is 161997769. The reversal of 161997759 is 957799161.

It is a happy number.

It is not a de Polignac number, because 161997759 - 2¹ = 161997757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161997751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 138712 + ... + 139874.

It is an arithmetic number, because the mean of its divisors is an integer number (4749120).

Almost surely, 2^161997759 is an apocalyptic number.

161997759 is a deficient number, since it is larger than the sum of its proper divisors (141945921).

161997759 is a wasteful number, since it uses less digits than its factorization.

161997759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1257 (or 1251 counting only the distinct ones).

The product of its digits is 1071630, while the sum is 54.

The square root of 161997759 is about 12727.8340262591. The cubic root of 161997759 is about 545.1336641546.

The spelling of 161997759 in words is "one hundred sixty-one million, nine hundred ninety-seven thousand, seven hundred fifty-nine".