840088421 has 2 divisors, whose sum is σ = 840088422. Its totient is φ = 840088420.

The previous prime is 840088393. The next prime is 840088423. The reversal of 840088421 is 124880048.

840088421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 777852100 + 62236321 = 27890^2 + 7889^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840088421 is a prime.

Together with 840088423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840088423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420044210 + 420044211.

It is an arithmetic number, because the mean of its divisors is an integer number (420044211).

Almost surely, 2^840088421 is an apocalyptic number.

It is an amenable number.

840088421 is a deficient number, since it is larger than the sum of its proper divisors (1).

840088421 is an equidigital number, since it uses as much as digits as its factorization.

840088421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16384, while the sum is 35.

The square root of 840088421 is about 28984.2788594093. The cubic root of 840088421 is about 943.5719015065.

It can be divided in two parts, 84008 and 8421, that added together give a palindrome (92429).

The spelling of 840088421 in words is "eight hundred forty million, eighty-eight thousand, four hundred twenty-one".