840511421 has 2 divisors, whose sum is σ = 840511422. Its totient is φ = 840511420.

The previous prime is 840511393. The next prime is 840511423. The reversal of 840511421 is 124115048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 709156900 + 131354521 = 26630^2 + 11461^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840511421 is a prime.

Together with 840511423, 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 (840511423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420255710 + 420255711.

It is an arithmetic number, because the mean of its divisors is an integer number (420255711).

Almost surely, 2^840511421 is an apocalyptic number.

It is an amenable number.

840511421 is a deficient number, since it is larger than the sum of its proper divisors (1).

840511421 is an equidigital number, since it uses as much as digits as its factorization.

840511421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 840511421 is about 28991.5750003341. The cubic root of 840511421 is about 943.7302435465.

Adding to 840511421 its reverse (124115048), we get a palindrome (964626469).

The spelling of 840511421 in words is "eight hundred forty million, five hundred eleven thousand, four hundred twenty-one".