42785021821 has 2 divisors, whose sum is σ = 42785021822. Its totient is φ = 42785021820.

The previous prime is 42785021761. The next prime is 42785021827. The reversal of 42785021821 is 12812058724.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42170676025 + 614345796 = 205355^2 + 24786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42785021821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42785021827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21392510910 + 21392510911.

It is an arithmetic number, because the mean of its divisors is an integer number (21392510911).

Almost surely, 2^42785021821 is an apocalyptic number.

It is an amenable number.

42785021821 is a deficient number, since it is larger than the sum of its proper divisors (1).

42785021821 is an equidigital number, since it uses as much as digits as its factorization.

42785021821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 71680, while the sum is 40.

The spelling of 42785021821 in words is "forty-two billion, seven hundred eighty-five million, twenty-one thousand, eight hundred twenty-one".