646863839 has 4 divisors (see below), whose sum is σ = 647000520. Its totient is φ = 646727160.

The previous prime is 646863829. The next prime is 646863851. The reversal of 646863839 is 938368646.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 646863839 - 2⁴ = 646863823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646863809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60977 + ... + 70794.

It is an arithmetic number, because the mean of its divisors is an integer number (161750130).

Almost surely, 2^646863839 is an apocalyptic number.

646863839 is a deficient number, since it is larger than the sum of its proper divisors (136681).

646863839 is a wasteful number, since it uses less digits than its factorization.

646863839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136680.

The product of its digits is 4478976, while the sum is 53.

The square root of 646863839 is about 25433.5180224836. The cubic root of 646863839 is about 864.8436970191.

It can be divided in two parts, 6468 and 63839, that added together give a palindrome (70307).

The spelling of 646863839 in words is "six hundred forty-six million, eight hundred sixty-three thousand, eight hundred thirty-nine".