163561765 has 4 divisors (see below), whose sum is σ = 196274124. Its totient is φ = 130849408.

The previous prime is 163561759. The next prime is 163561771. The reversal of 163561765 is 567165361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 567165361 = 7 ⋅81023623.

It is an interprime number because it is at equal distance from previous prime (163561759) and next prime (163561771).

It can be written as a sum of positive squares in 2 ways, for example, as 124411716 + 39150049 = 11154^2 + 6257^2 .

It is a cyclic number.

It is not a de Polignac number, because 163561765 - 2³ = 163561757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16356172 + ... + 16356181.

It is an arithmetic number, because the mean of its divisors is an integer number (49068531).

Almost surely, 2^163561765 is an apocalyptic number.

It is an amenable number.

163561765 is a deficient number, since it is larger than the sum of its proper divisors (32712359).

163561765 is an equidigital number, since it uses as much as digits as its factorization.

163561765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32712358.

The product of its digits is 113400, while the sum is 40.

The square root of 163561765 is about 12789.1268271137. The cubic root of 163561765 is about 546.8823779794.

The spelling of 163561765 in words is "one hundred sixty-three million, five hundred sixty-one thousand, seven hundred sixty-five".