161695661 has 8 divisors (see below), whose sum is σ = 167032344. Its totient is φ = 156409920.

The previous prime is 161695649. The next prime is 161695669. The reversal of 161695661 is 166596161.

It can be written as a sum of positive squares in 4 ways, for example, as 59382436 + 102313225 = 7706^2 + 10115^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161695661 is a prime.

It is a super-2 number, since 2×161695661² = 52290973572453842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161695669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6230 + ... + 19031.

It is an arithmetic number, because the mean of its divisors is an integer number (20879043).

Almost surely, 2^161695661 is an apocalyptic number.

It is an amenable number.

161695661 is a deficient number, since it is larger than the sum of its proper divisors (5336683).

161695661 is a wasteful number, since it uses less digits than its factorization.

161695661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25471.

The product of its digits is 58320, while the sum is 41.

The square root of 161695661 is about 12715.9608760015. The cubic root of 161695661 is about 544.7945930755.

The spelling of 161695661 in words is "one hundred sixty-one million, six hundred ninety-five thousand, six hundred sixty-one".