165225421 has 2 divisors, whose sum is σ = 165225422. Its totient is φ = 165225420.

The previous prime is 165225409. The next prime is 165225427. The reversal of 165225421 is 124522561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 139358025 + 25867396 = 11805^2 + 5086^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165225421 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165225421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165225427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82612710 + 82612711.

It is an arithmetic number, because the mean of its divisors is an integer number (82612711).

Almost surely, 2^165225421 is an apocalyptic number.

It is an amenable number.

165225421 is a deficient number, since it is larger than the sum of its proper divisors (1).

165225421 is an equidigital number, since it uses as much as digits as its factorization.

165225421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4800, while the sum is 28.

The square root of 165225421 is about 12854.0040843311. The cubic root of 165225421 is about 548.7303174569.

Adding to 165225421 its reverse (124522561), we get a palindrome (289747982).

The spelling of 165225421 in words is "one hundred sixty-five million, two hundred twenty-five thousand, four hundred twenty-one".