165821280 has 48 divisors (see below), whose sum is σ = 522338544. Its totient is φ = 44218880.

The previous prime is 165821269. The next prime is 165821297. The reversal of 165821280 is 82128561.

It is a tau number, because it is divible by the number of its divisors (48).

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

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, 172251 + ... + 173210.

It is an arithmetic number, because the mean of its divisors is an integer number (10882053).

Almost surely, 2^165821280 is an apocalyptic number.

165821280 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165821280 is an abundant number, since it is smaller than the sum of its proper divisors (356517264).

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

165821280 is a wasteful number, since it uses less digits than its factorization.

165821280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345479 (or 345471 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 33.

The square root of 165821280 is about 12877.1611778373. The cubic root of 165821280 is about 549.3891620661.

The spelling of 165821280 in words is "one hundred sixty-five million, eight hundred twenty-one thousand, two hundred eighty".