42420521 has 24 divisors (see below), whose sum is σ = 52791840. Its totient is φ = 33696000.

The previous prime is 42420509. The next prime is 42420529. The reversal of 42420521 is 12502424.

It is a happy number.

It is not a de Polignac number, because 42420521 - 2¹⁸ = 42158377 is a prime.

It is a super-2 number, since 2×42420521² = 3599001203822882, which contains 22 as substring.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42420493 and 42420502.

It is not an unprimeable number, because it can be changed into a prime (42420529) 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 in 23 ways as a sum of consecutive naturals, for example, 34721 + ... + 35921.

It is an arithmetic number, because the mean of its divisors is an integer number (2199660).

Almost surely, 2^42420521 is an apocalyptic number.

It is an amenable number.

42420521 is a deficient number, since it is larger than the sum of its proper divisors (10371319).

42420521 is a wasteful number, since it uses less digits than its factorization.

42420521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1257 (or 1244 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 42420521 is about 6513.1037915882. The cubic root of 42420521 is about 348.7589269007.

Adding to 42420521 its reverse (12502424), we get a palindrome (54922945).

The spelling of 42420521 in words is "forty-two million, four hundred twenty thousand, five hundred twenty-one".