165221651 has 8 divisors (see below), whose sum is σ = 189721344. Its totient is φ = 140946120.

The previous prime is 165221603. The next prime is 165221669. The reversal of 165221651 is 156122561.

It is a happy number.

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

It is not a de Polignac number, because 165221651 - 2¹⁴ = 165205267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165221681) 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 7 ways as a sum of consecutive naturals, for example, 54455 + ... + 57408.

It is an arithmetic number, because the mean of its divisors is an integer number (23715168).

Almost surely, 2^165221651 is an apocalyptic number.

165221651 is a deficient number, since it is larger than the sum of its proper divisors (24499693).

165221651 is a wasteful number, since it uses less digits than its factorization.

165221651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112081.

The product of its digits is 3600, while the sum is 29.

The square root of 165221651 is about 12853.8574365830. The cubic root of 165221651 is about 548.7261439082.

The spelling of 165221651 in words is "one hundred sixty-five million, two hundred twenty-one thousand, six hundred fifty-one".