42591838021 has 2 divisors, whose sum is σ = 42591838022. Its totient is φ = 42591838020.

The previous prime is 42591838013. The next prime is 42591838031. The reversal of 42591838021 is 12083819524.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42146037025 + 445800996 = 205295^2 + 21114^2 .

It is a cyclic number.

It is not a de Polignac number, because 42591838021 - 2³ = 42591838013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42591838031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21295919010 + 21295919011.

It is an arithmetic number, because the mean of its divisors is an integer number (21295919011).

Almost surely, 2^42591838021 is an apocalyptic number.

It is an amenable number.

42591838021 is a deficient number, since it is larger than the sum of its proper divisors (1).

42591838021 is an equidigital number, since it uses as much as digits as its factorization.

42591838021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 42591838021 in words is "forty-two billion, five hundred ninety-one million, eight hundred thirty-eight thousand, twenty-one".