165151661 has 4 divisors (see below), whose sum is σ = 172332192. Its totient is φ = 157971132.

The previous prime is 165151631. The next prime is 165151697. The reversal of 165151661 is 166151561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166151561 = 19 ⋅8744819.

It is a cyclic number.

It is not a de Polignac number, because 165151661 - 2¹⁰ = 165150637 is a prime.

It is a super-2 number, since 2×165151661² = 54550142262117842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165151621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3590231 + ... + 3590276.

It is an arithmetic number, because the mean of its divisors is an integer number (43083048).

Almost surely, 2^165151661 is an apocalyptic number.

It is an amenable number.

165151661 is a deficient number, since it is larger than the sum of its proper divisors (7180531).

165151661 is an equidigital number, since it uses as much as digits as its factorization.

165151661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7180530.

The product of its digits is 5400, while the sum is 32.

The square root of 165151661 is about 12851.1346191688. The cubic root of 165151661 is about 548.6486504989.

The spelling of 165151661 in words is "one hundred sixty-five million, one hundred fifty-one thousand, six hundred sixty-one".