42531521 has 2 divisors, whose sum is σ = 42531522. Its totient is φ = 42531520.

The previous prime is 42531509. The next prime is 42531523. The reversal of 42531521 is 12513524.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41783296 + 748225 = 6464^2 + 865^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42531521 is a prime.

Together with 42531523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (42531523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21265760 + 21265761.

It is an arithmetic number, because the mean of its divisors is an integer number (21265761).

Almost surely, 2^42531521 is an apocalyptic number.

It is an amenable number.

42531521 is a deficient number, since it is larger than the sum of its proper divisors (1).

42531521 is an equidigital number, since it uses as much as digits as its factorization.

42531521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1200, while the sum is 23.

The square root of 42531521 is about 6521.6195074537. The cubic root of 42531521 is about 349.0628562523.

The spelling of 42531521 in words is "forty-two million, five hundred thirty-one thousand, five hundred twenty-one".