161909566 has 32 divisors (see below), whose sum is σ = 300303360. Its totient is φ = 63753696.

The previous prime is 161909551. The next prime is 161909567. The reversal of 161909566 is 665909161.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161909567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39355 + ... + 43273.

It is an arithmetic number, because the mean of its divisors is an integer number (9384480).

Almost surely, 2^161909566 is an apocalyptic number.

161909566 is a deficient number, since it is larger than the sum of its proper divisors (138393794).

161909566 is a wasteful number, since it uses less digits than its factorization.

161909566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4168.

The product of its (nonzero) digits is 87480, while the sum is 43.

The square root of 161909566 is about 12724.3689823897. The cubic root of 161909566 is about 545.0347210155.

It can be divided in two parts, 1619095 and 66, that added together give a palindrome (1619161).

The spelling of 161909566 in words is "one hundred sixty-one million, nine hundred nine thousand, five hundred sixty-six".