161345561 has 12 divisors (see below), whose sum is σ = 175337316. Its totient is φ = 147588000.

The previous prime is 161345551. The next prime is 161345579. The reversal of 161345561 is 165543161.

161345561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 100801600 + 60543961 = 10040^2 + 7781^2 .

It is not a de Polignac number, because 161345561 - 2⁶ = 161345497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161345551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 642686 + ... + 642936.

It is an arithmetic number, because the mean of its divisors is an integer number (14611443).

Almost surely, 2^161345561 is an apocalyptic number.

It is an amenable number.

161345561 is a deficient number, since it is larger than the sum of its proper divisors (13991755).

161345561 is an equidigital number, since it uses as much as digits as its factorization.

161345561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712 (or 461 counting only the distinct ones).

The product of its digits is 10800, while the sum is 32.

The square root of 161345561 is about 12702.1872525955. The cubic root of 161345561 is about 544.4011164079.

It can be divided in two parts, 1613 and 45561, that added together give a palindrome (47174).

The spelling of 161345561 in words is "one hundred sixty-one million, three hundred forty-five thousand, five hundred sixty-one".