163644661 has 4 divisors (see below), whose sum is σ = 163888492. Its totient is φ = 163400832.

The previous prime is 163644659. The next prime is 163644667. The reversal of 163644661 is 166446361.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 82464561 + 81180100 = 9081^2 + 9010^2 .

It is a cyclic number.

It is not a de Polignac number, because 163644661 - 2¹ = 163644659 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 163644661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163644667) 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, 120906 + ... + 122251.

It is an arithmetic number, because the mean of its divisors is an integer number (40972123).

Almost surely, 2^163644661 is an apocalyptic number.

It is an amenable number.

163644661 is a deficient number, since it is larger than the sum of its proper divisors (243831).

163644661 is an equidigital number, since it uses as much as digits as its factorization.

163644661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243830.

The product of its digits is 62208, while the sum is 37.

The square root of 163644661 is about 12792.3672946019. The cubic root of 163644661 is about 546.9747522679.

It can be divided in two parts, 16364 and 4661, that added together give a square (21025 = 145²).

The spelling of 163644661 in words is "one hundred sixty-three million, six hundred forty-four thousand, six hundred sixty-one".