165042421 has 2 divisors, whose sum is σ = 165042422. Its totient is φ = 165042420.

The previous prime is 165042407. The next prime is 165042431. The reversal of 165042421 is 124240561.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164839921 + 202500 = 12839^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 165042421 - 2¹³ = 165034229 is a prime.

It is equal to p_9241171 and since 165042421 and 9241171 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165042431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82521210 + 82521211.

It is an arithmetic number, because the mean of its divisors is an integer number (82521211).

Almost surely, 2^165042421 is an apocalyptic number.

It is an amenable number.

165042421 is a deficient number, since it is larger than the sum of its proper divisors (1).

165042421 is an equidigital number, since it uses as much as digits as its factorization.

165042421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 165042421 is about 12846.8837077324. The cubic root of 165042421 is about 548.5276554538.

Adding to 165042421 its reverse (124240561), we get a palindrome (289282982).

The spelling of 165042421 in words is "one hundred sixty-five million, forty-two thousand, four hundred twenty-one".