155166221 has 4 divisors (see below), whose sum is σ = 177332832. Its totient is φ = 132999612.

The previous prime is 155166173. The next prime is 155166247. The reversal of 155166221 is 122661551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 155166221 - 2¹⁸ = 154904077 is a prime.

It is a super-2 number, since 2×155166221² = 48153112278841682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155166251) 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, 11083295 + ... + 11083308.

It is an arithmetic number, because the mean of its divisors is an integer number (44333208).

Almost surely, 2^155166221 is an apocalyptic number.

It is an amenable number.

155166221 is a deficient number, since it is larger than the sum of its proper divisors (22166611).

155166221 is an equidigital number, since it uses as much as digits as its factorization.

155166221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22166610.

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

The square root of 155166221 is about 12456.5734052347. The cubic root of 155166221 is about 537.3604855861.

The spelling of 155166221 in words is "one hundred fifty-five million, one hundred sixty-six thousand, two hundred twenty-one".