639743 has 4 divisors (see below), whose sum is σ = 688968. Its totient is φ = 590520.

The previous prime is 639739. The next prime is 639757. The reversal of 639743 is 347936.

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 639743 - 2² = 639739 is a prime.

It is a super-2 number, since 2×639743² = 818542212098, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24593 + ... + 24618.

It is an arithmetic number, because the mean of its divisors is an integer number (172242).

2⁶³⁹⁷⁴³ is an apocalyptic number.

639743 is a deficient number, since it is larger than the sum of its proper divisors (49225).

639743 is a wasteful number, since it uses less digits than its factorization.

639743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49224.

The product of its digits is 13608, while the sum is 32.

The square root of 639743 is about 799.8393588715. The cubic root of 639743 is about 86.1658508545.

The spelling of 639743 in words is "six hundred thirty-nine thousand, seven hundred forty-three".