40042390021 has 2 divisors, whose sum is σ = 40042390022. Its totient is φ = 40042390020.

The previous prime is 40042389997. The next prime is 40042390033. The reversal of 40042390021 is 12009324004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25119080100 + 14923309921 = 158490^2 + 122161^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40042390021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40042390051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20021195010 + 20021195011.

It is an arithmetic number, because the mean of its divisors is an integer number (20021195011).

Almost surely, 2^40042390021 is an apocalyptic number.

It is an amenable number.

40042390021 is a deficient number, since it is larger than the sum of its proper divisors (1).

40042390021 is an equidigital number, since it uses as much as digits as its factorization.

40042390021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 25.

The spelling of 40042390021 in words is "forty billion, forty-two million, three hundred ninety thousand, twenty-one".