840648989 has 2 divisors, whose sum is σ = 840648990. Its totient is φ = 840648988.

The previous prime is 840648973. The next prime is 840649001. The reversal of 840648989 is 989846048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 709156900 + 131492089 = 26630^2 + 11467^2 .

It is a cyclic number.

It is not a de Polignac number, because 840648989 - 2⁴ = 840648973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840648959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420324494 + 420324495.

It is an arithmetic number, because the mean of its divisors is an integer number (420324495).

Almost surely, 2^840648989 is an apocalyptic number.

It is an amenable number.

840648989 is a deficient number, since it is larger than the sum of its proper divisors (1).

840648989 is an equidigital number, since it uses as much as digits as its factorization.

840648989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3981312, while the sum is 56.

The square root of 840648989 is about 28993.9474545982. The cubic root of 840648989 is about 943.7817280739.

The spelling of 840648989 in words is "eight hundred forty million, six hundred forty-eight thousand, nine hundred eighty-nine".