163665661 has 4 divisors (see below), whose sum is σ = 165254752. Its totient is φ = 162076572.

The previous prime is 163665659. The next prime is 163665679. The reversal of 163665661 is 166566361.

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.

It is a cyclic number.

It is not a de Polignac number, because 163665661 - 2¹ = 163665659 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 (163765661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 794391 + ... + 794596.

It is an arithmetic number, because the mean of its divisors is an integer number (41313688).

Almost surely, 2^163665661 is an apocalyptic number.

It is an amenable number.

163665661 is a deficient number, since it is larger than the sum of its proper divisors (1589091).

163665661 is a wasteful number, since it uses less digits than its factorization.

163665661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1589090.

The product of its digits is 116640, while the sum is 40.

The square root of 163665661 is about 12793.1880702192. The cubic root of 163665661 is about 546.9981484451.

The spelling of 163665661 in words is "one hundred sixty-three million, six hundred sixty-five thousand, six hundred sixty-one".