7864639 has 2 divisors, whose sum is σ = 7864640. Its totient is φ = 7864638.

The previous prime is 7864627. The next prime is 7864673. The reversal of 7864639 is 9364687.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 7864639 - 2⁹ = 7864127 is a prime.

It is a d-powerful number, because it can be written as 7⁸ + 8⁷ + 6⁴ + 4 + 6⁴ + 3⁴ + 9 .

It is a junction number, because it is equal to n+sod(n) for n = 7864595 and 7864604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7864699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3932319 + 3932320.

It is an arithmetic number, because the mean of its divisors is an integer number (3932320).

Almost surely, 2^7864639 is an apocalyptic number.

7864639 is a deficient number, since it is larger than the sum of its proper divisors (1).

7864639 is an equidigital number, since it uses as much as digits as its factorization.

7864639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 43.

The square root of 7864639 is about 2804.3963699877. The cubic root of 7864639 is about 198.8655691662.

The spelling of 7864639 in words is "seven million, eight hundred sixty-four thousand, six hundred thirty-nine".