42164821 has 2 divisors, whose sum is σ = 42164822. Its totient is φ = 42164820.

The previous prime is 42164813. The next prime is 42164849. The reversal of 42164821 is 12846124.

It is an a-pointer prime, because the next prime (42164849) can be obtained adding 42164821 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23415921 + 18748900 = 4839^2 + 4330^2 .

It is a cyclic number.

It is not a de Polignac number, because 42164821 - 2³ = 42164813 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 42164821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42164891) 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, 21082410 + 21082411.

It is an arithmetic number, because the mean of its divisors is an integer number (21082411).

Almost surely, 2^42164821 is an apocalyptic number.

It is an amenable number.

42164821 is a deficient number, since it is larger than the sum of its proper divisors (1).

42164821 is an equidigital number, since it uses as much as digits as its factorization.

42164821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 28.

The square root of 42164821 is about 6493.4444634570. Note that the first 4 decimals coincide. The cubic root of 42164821 is about 348.0567711362.

The spelling of 42164821 in words is "forty-two million, one hundred sixty-four thousand, eight hundred twenty-one".