42080021 has 2 divisors, whose sum is σ = 42080022. Its totient is φ = 42080020.

The previous prime is 42080011. The next prime is 42080023. The reversal of 42080021 is 12008024.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34456900 + 7623121 = 5870^2 + 2761^2 .

It is a cyclic number.

It is not a de Polignac number, because 42080021 - 2²² = 37885717 is a prime.

Together with 42080023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42080023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21040010 + 21040011.

It is an arithmetic number, because the mean of its divisors is an integer number (21040011).

Almost surely, 2^42080021 is an apocalyptic number.

It is an amenable number.

42080021 is a deficient number, since it is larger than the sum of its proper divisors (1).

42080021 is an equidigital number, since it uses as much as digits as its factorization.

42080021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 42080021 is about 6486.9115147349. The cubic root of 42080021 is about 347.8232824744.

Adding to 42080021 its reverse (12008024), we get a palindrome (54088045).

The spelling of 42080021 in words is "forty-two million, eighty thousand, twenty-one".