165221111 has 8 divisors (see below), whose sum is σ = 180364800. Its totient is φ = 150098040.

The previous prime is 165221107. The next prime is 165221171. The reversal of 165221111 is 111122561.

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

It is a cyclic number.

It is not a de Polignac number, because 165221111 - 2² = 165221107 is a prime.

It is a super-4 number, since 4×165221111⁴ (a number of 34 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165221101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15080 + ... + 23618.

It is an arithmetic number, because the mean of its divisors is an integer number (22545600).

Almost surely, 2^165221111 is an apocalyptic number.

165221111 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

165221111 is a deficient number, since it is larger than the sum of its proper divisors (15143689).

165221111 is a wasteful number, since it uses less digits than its factorization.

165221111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10309.

The product of its digits is 120, while the sum is 20.

The square root of 165221111 is about 12853.8364311983. The cubic root of 165221111 is about 548.7255461003.

Adding to 165221111 its reverse (111122561), we get a palindrome (276343672).

The spelling of 165221111 in words is "one hundred sixty-five million, two hundred twenty-one thousand, one hundred eleven".