6439861 has 4 divisors (see below), whose sum is σ = 6503724. Its totient is φ = 6376000.

The previous prime is 6439837. The next prime is 6439903. The reversal of 6439861 is 1689346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5640625 + 799236 = 2375^2 + 894^2 .

It is a cyclic number.

It is not a de Polignac number, because 6439861 - 2¹¹ = 6437813 is a prime.

It is an Ulam number.

It is a Duffinian number.

6439861 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 6439861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6439561) 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 in 3 ways as a sum of consecutive naturals, for example, 31780 + ... + 31981.

It is an arithmetic number, because the mean of its divisors is an integer number (1625931).

Almost surely, 2^6439861 is an apocalyptic number.

It is an amenable number.

6439861 is a deficient number, since it is larger than the sum of its proper divisors (63863).

6439861 is a wasteful number, since it uses less digits than its factorization.

6439861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63862.

The product of its digits is 31104, while the sum is 37.

The square root of 6439861 is about 2537.6881211055. The cubic root of 6439861 is about 186.0482108041.

The spelling of 6439861 in words is "six million, four hundred thirty-nine thousand, eight hundred sixty-one".