165071981 has 8 divisors (see below), whose sum is σ = 175553280. Its totient is φ = 154770048.

The previous prime is 165071971. The next prime is 165071999. The reversal of 165071981 is 189170561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165071981 - 2²² = 160877677 is a prime.

It is a super-2 number, since 2×165071981² = 54497517822528722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165071971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42941 + ... + 46626.

It is an arithmetic number, because the mean of its divisors is an integer number (21944160).

Almost surely, 2^165071981 is an apocalyptic number.

It is an amenable number.

165071981 is a deficient number, since it is larger than the sum of its proper divisors (10481299).

165071981 is an equidigital number, since it uses as much as digits as its factorization.

165071981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89683.

The product of its (nonzero) digits is 15120, while the sum is 38.

The square root of 165071981 is about 12848.0341297803. The cubic root of 165071981 is about 548.5604015996.

The spelling of 165071981 in words is "one hundred sixty-five million, seventy-one thousand, nine hundred eighty-one".