42201821 has 2 divisors, whose sum is σ = 42201822. Its totient is φ = 42201820.

The previous prime is 42201799. The next prime is 42201829. The reversal of 42201821 is 12810224.

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., 34987225 + 7214596 = 5915^2 + 2686^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42201821 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 42201793 and 42201802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42201829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21100910 + 21100911.

It is an arithmetic number, because the mean of its divisors is an integer number (21100911).

Almost surely, 2^42201821 is an apocalyptic number.

It is an amenable number.

42201821 is a deficient number, since it is larger than the sum of its proper divisors (1).

42201821 is an equidigital number, since it uses as much as digits as its factorization.

42201821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 42201821 is about 6496.2928659352. The cubic root of 42201821 is about 348.1585489942.

The spelling of 42201821 in words is "forty-two million, two hundred one thousand, eight hundred twenty-one".