165221401 has 4 divisors (see below), whose sum is σ = 166176612. Its totient is φ = 164266192.

The previous prime is 165221387. The next prime is 165221423. The reversal of 165221401 is 104122561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 104755225 + 60466176 = 10235^2 + 7776^2 .

It is a cyclic number.

It is not a de Polignac number, because 165221401 - 2²¹ = 163124249 is a prime.

It is a super-2 number, since 2×165221401² = 54596222696805602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165221491) 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, 477346 + ... + 477691.

It is an arithmetic number, because the mean of its divisors is an integer number (41544153).

Almost surely, 2^165221401 is an apocalyptic number.

It is an amenable number.

165221401 is a deficient number, since it is larger than the sum of its proper divisors (955211).

165221401 is an equidigital number, since it uses as much as digits as its factorization.

165221401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 955210.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 165221401 is about 12853.8477118721. The cubic root of 165221401 is about 548.7258671454.

Adding to 165221401 its reverse (104122561), we get a palindrome (269343962).

The spelling of 165221401 in words is "one hundred sixty-five million, two hundred twenty-one thousand, four hundred one".