42290021 has 2 divisors, whose sum is σ = 42290022. Its totient is φ = 42290020.

The previous prime is 42290009. The next prime is 42290047. The reversal of 42290021 is 12009224.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29430625 + 12859396 = 5425^2 + 3586^2 .

It is a cyclic number.

It is not a de Polignac number, because 42290021 - 2¹⁰ = 42288997 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 42289975 and 42290002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42290051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21145010 + 21145011.

It is an arithmetic number, because the mean of its divisors is an integer number (21145011).

Almost surely, 2^42290021 is an apocalyptic number.

It is an amenable number.

42290021 is a deficient number, since it is larger than the sum of its proper divisors (1).

42290021 is an equidigital number, since it uses as much as digits as its factorization.

42290021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 42290021 is about 6503.0778097759. The cubic root of 42290021 is about 348.4009257099.

Adding to 42290021 its reverse (12009224), we get a palindrome (54299245).

The spelling of 42290021 in words is "forty-two million, two hundred ninety thousand, twenty-one".