1661601165 has 64 divisors (see below), whose sum is σ = 3229217280. Its totient is φ = 714685440.

The previous prime is 1661601119. The next prime is 1661601191. The reversal of 1661601165 is 5611061661.

It is not a de Polignac number, because 1661601165 - 2⁶ = 1661601101 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 514255 + ... + 517475.

It is an arithmetic number, because the mean of its divisors is an integer number (50456520).

Almost surely, 2^1661601165 is an apocalyptic number.

1661601165 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661601165 is a deficient number, since it is larger than the sum of its proper divisors (1567616115).

1661601165 is an equidigital number, since it uses as much as digits as its factorization.

1661601165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3287 (or 3253 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 1661601165 is about 40762.7423635849. The cubic root of 1661601165 is about 1184.4287192747.

The spelling of 1661601165 in words is "one billion, six hundred sixty-one million, six hundred one thousand, one hundred sixty-five".