165521566 has 8 divisors (see below), whose sum is σ = 283751280. Its totient is φ = 70937808.

The previous prime is 165521563. The next prime is 165521579. The reversal of 165521566 is 665125561.

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

It is a super-2 number, since 2×165521566² = 54794777622184712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165521563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5911471 + ... + 5911498.

It is an arithmetic number, because the mean of its divisors is an integer number (35468910).

Almost surely, 2^165521566 is an apocalyptic number.

165521566 is a deficient number, since it is larger than the sum of its proper divisors (118229714).

165521566 is a wasteful number, since it uses less digits than its factorization.

165521566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11822978.

The product of its digits is 54000, while the sum is 37.

The square root of 165521566 is about 12865.5184893575. The cubic root of 165521566 is about 549.0579642692.

It can be divided in two parts, 165 and 521566, that added together give a triangular number (521731 = T₁₀₂₁).

The spelling of 165521566 in words is "one hundred sixty-five million, five hundred twenty-one thousand, five hundred sixty-six".