165221505 has 16 divisors (see below), whose sum is σ = 293727360. Its totient is φ = 88118064.

The previous prime is 165221501. The next prime is 165221519. The reversal of 165221505 is 505122561.

165221505 is a `hidden beast` number, since 1 + 652 + 2 + 1 + 5 + 0 + 5 = 666.

It is not a de Polignac number, because 165221505 - 2² = 165221501 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (165221501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 611797 + ... + 612066.

It is an arithmetic number, because the mean of its divisors is an integer number (18357960).

Almost surely, 2^165221505 is an apocalyptic number.

165221505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

165221505 is a deficient number, since it is larger than the sum of its proper divisors (128505855).

165221505 is a wasteful number, since it uses less digits than its factorization.

165221505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1223877 (or 1223871 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The square root of 165221505 is about 12853.8517573527. The cubic root of 165221505 is about 548.7259822788.

The spelling of 165221505 in words is "one hundred sixty-five million, two hundred twenty-one thousand, five hundred five".