163531661 has 4 divisors (see below), whose sum is σ = 163660800. Its totient is φ = 163402524.

The previous prime is 163531649. The next prime is 163531681. The reversal of 163531661 is 166135361.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166135361 = 7 ⋅23733623.

It is a cyclic number.

It is not a de Polignac number, because 163531661 - 2¹⁴ = 163515277 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 (163531681) 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, 62651 + ... + 65208.

It is an arithmetic number, because the mean of its divisors is an integer number (40915200).

Almost surely, 2^163531661 is an apocalyptic number.

It is an amenable number.

163531661 is a deficient number, since it is larger than the sum of its proper divisors (129139).

163531661 is a wasteful number, since it uses less digits than its factorization.

163531661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129138.

The product of its digits is 9720, while the sum is 32.

The square root of 163531661 is about 12787.9498356852. The cubic root of 163531661 is about 546.8488241773.

The spelling of 163531661 in words is "one hundred sixty-three million, five hundred thirty-one thousand, six hundred sixty-one".