42402421 has 2 divisors, whose sum is σ = 42402422. Its totient is φ = 42402420.

The previous prime is 42402419. The next prime is 42402427. The reversal of 42402421 is 12420424.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30747025 + 11655396 = 5545^2 + 3414^2 .

It is a cyclic number.

It is not a de Polignac number, because 42402421 - 2¹ = 42402419 is a prime.

It is a super-2 number, since 2×42402421² = 3595930613322482, which contains 22 as substring.

Together with 42402419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42402427) 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, 21201210 + 21201211.

It is an arithmetic number, because the mean of its divisors is an integer number (21201211).

Almost surely, 2^42402421 is an apocalyptic number.

It is an amenable number.

42402421 is a deficient number, since it is larger than the sum of its proper divisors (1).

42402421 is an equidigital number, since it uses as much as digits as its factorization.

42402421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 42402421 is about 6511.7141368460. The cubic root of 42402421 is about 348.7093169914.

Adding to 42402421 its reverse (12420424), we get a palindrome (54822845).

The spelling of 42402421 in words is "forty-two million, four hundred two thousand, four hundred twenty-one".