42165421 has 2 divisors, whose sum is σ = 42165422. Its totient is φ = 42165420.

The previous prime is 42165401. The next prime is 42165467. The reversal of 42165421 is 12456124.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38502025 + 3663396 = 6205^2 + 1914^2 .

It is a cyclic number.

It is not a de Polignac number, because 42165421 - 2⁷ = 42165293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42165401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21082710 + 21082711.

It is an arithmetic number, because the mean of its divisors is an integer number (21082711).

Almost surely, 2^42165421 is an apocalyptic number.

It is an amenable number.

42165421 is a deficient number, since it is larger than the sum of its proper divisors (1).

42165421 is an equidigital number, since it uses as much as digits as its factorization.

42165421 is an evil number, because the sum of its binary digits is even.

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

The square root of 42165421 is about 6493.4906637340. The cubic root of 42165421 is about 348.0584220628.

The spelling of 42165421 in words is "forty-two million, one hundred sixty-five thousand, four hundred twenty-one".