165221550 has 144 divisors (see below), whose sum is σ = 486927168. Its totient is φ = 39916800.

The previous prime is 165221533. The next prime is 165221561. The reversal of 165221550 is 55122561.

165221550 is a `hidden beast` number, since 1 + 652 + 2 + 1 + 5 + 5 + 0 = 666.

165221550 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 356619 + ... + 357081.

Almost surely, 2^165221550 is an apocalyptic number.

165221550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 165221550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (243463584).

165221550 is an abundant number, since it is smaller than the sum of its proper divisors (321705618).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

165221550 is a wasteful number, since it uses less digits than its factorization.

165221550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555 (or 547 counting only the distinct ones).

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

The square root of 165221550 is about 12853.8535078007. The cubic root of 165221550 is about 548.7260320961.

The spelling of 165221550 in words is "one hundred sixty-five million, two hundred twenty-one thousand, five hundred fifty".