161331613 has 4 divisors (see below), whose sum is σ = 161357020. Its totient is φ = 161306208.

The previous prime is 161331607. The next prime is 161331631. The reversal of 161331613 is 316133161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 132204004 + 29127609 = 11498^2 + 5397^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161331613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161331013) 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 3 ways as a sum of consecutive naturals, for example, 6073 + ... + 18961.

It is an arithmetic number, because the mean of its divisors is an integer number (40339255).

Almost surely, 2^161331613 is an apocalyptic number.

It is an amenable number.

161331613 is a deficient number, since it is larger than the sum of its proper divisors (25407).

161331613 is a wasteful number, since it uses less digits than its factorization.

161331613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25406.

The product of its digits is 972, while the sum is 25.

The square root of 161331613 is about 12701.6382014290. The cubic root of 161331613 is about 544.3854284944.

Adding to 161331613 its reverse (316133161), we get a palindrome (477464774).

The spelling of 161331613 in words is "one hundred sixty-one million, three hundred thirty-one thousand, six hundred thirteen".