161611506 has 72 divisors (see below), whose sum is σ = 411744060. Its totient is φ = 45674496.

The previous prime is 161611487. The next prime is 161611517. The reversal of 161611506 is 605116161.

It can be written as a sum of positive squares in 2 ways, for example, as 161417025 + 194481 = 12705^2 + 441^2 .

It is a super-2 number, since 2×161611506² = 52236557743176072, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 161611506.

It is a congruent number.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 84610 + ... + 86498.

Almost surely, 2^161611506 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161611506, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (205872030).

161611506 is an abundant number, since it is smaller than the sum of its proper divisors (250132554).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161611506 is a wasteful number, since it uses less digits than its factorization.

161611506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2008 (or 1998 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 161611506 is about 12712.6514150275. The cubic root of 161611506 is about 544.7000633382.

Adding to 161611506 its reverse (605116161), we get a palindrome (766727667).

The spelling of 161611506 in words is "one hundred sixty-one million, six hundred eleven thousand, five hundred six".