165421601 has 2 divisors, whose sum is σ = 165421602. Its totient is φ = 165421600.

The previous prime is 165421591. The next prime is 165421603. The reversal of 165421601 is 106124561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83247376 + 82174225 = 9124^2 + 9065^2 .

It is a cyclic number.

It is not a de Polignac number, because 165421601 - 2¹⁴ = 165405217 is a prime.

Together with 165421603, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_9261107 and since 165421601 and 9261107 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (165421603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82710800 + 82710801.

It is an arithmetic number, because the mean of its divisors is an integer number (82710801).

Almost surely, 2^165421601 is an apocalyptic number.

It is an amenable number.

165421601 is a deficient number, since it is larger than the sum of its proper divisors (1).

165421601 is an equidigital number, since it uses as much as digits as its factorization.

165421601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 165421601 is about 12861.6329056617. The cubic root of 165421601 is about 548.9474094257.

The spelling of 165421601 in words is "one hundred sixty-five million, four hundred twenty-one thousand, six hundred one".