165221907 has 4 divisors (see below), whose sum is σ = 220295880. Its totient is φ = 110147936.

The previous prime is 165221893. The next prime is 165221981. The reversal of 165221907 is 709122561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 165221907 - 2¹⁰ = 165220883 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165221107) 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, 27536982 + ... + 27536987.

It is an arithmetic number, because the mean of its divisors is an integer number (55073970).

Almost surely, 2^165221907 is an apocalyptic number.

165221907 is a deficient number, since it is larger than the sum of its proper divisors (55073973).

165221907 is an equidigital number, since it uses as much as digits as its factorization.

165221907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55073972.

The product of its (nonzero) digits is 7560, while the sum is 33.

The square root of 165221907 is about 12853.8673946793. The cubic root of 165221907 is about 548.7264273130.

The spelling of 165221907 in words is "one hundred sixty-five million, two hundred twenty-one thousand, nine hundred seven".