161665877 has 4 divisors (see below), whose sum is σ = 161930220. Its totient is φ = 161401536.

The previous prime is 161665843. The next prime is 161665897. The reversal of 161665877 is 778566161.

161665877 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 26152996 + 135512881 = 5114^2 + 11641^2 .

It is a cyclic number.

It is not a de Polignac number, because 161665877 - 2¹⁸ = 161403733 is a prime.

It is a super-2 number, since 2×161665877² = 52271711572358258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161665817) 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, 131252 + ... + 132477.

It is an arithmetic number, because the mean of its divisors is an integer number (40482555).

Almost surely, 2^161665877 is an apocalyptic number.

It is an amenable number.

161665877 is a deficient number, since it is larger than the sum of its proper divisors (264343).

161665877 is an equidigital number, since it uses as much as digits as its factorization.

161665877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264342.

The product of its digits is 423360, while the sum is 47.

The square root of 161665877 is about 12714.7896954688. The cubic root of 161665877 is about 544.7611410162.

The spelling of 161665877 in words is "one hundred sixty-one million, six hundred sixty-five thousand, eight hundred seventy-seven".