639626 has 16 divisors (see below), whose sum is σ = 1050504. Its totient is φ = 290304.

The previous prime is 639601. The next prime is 639631. The reversal of 639626 is 626936.

It can be written as a sum of positive squares in 4 ways, for example, as 390625 + 249001 = 625^2 + 499^2 .

It is an Ulam number.

It is a d-powerful number, because it can be written as 6³ + 3¹² + 6³ + 9⁵ + 2¹¹ + 6⁶ .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 639592 and 639601.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639626.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1730 + ... + 2066.

2⁶³⁹⁶²⁶ is an apocalyptic number.

639626 is a deficient number, since it is larger than the sum of its proper divisors (410878).

639626 is a wasteful number, since it uses less digits than its factorization.

639626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425.

The product of its digits is 11664, while the sum is 32.

The square root of 639626 is about 799.7662158406. The cubic root of 639626 is about 86.1605976934.

The spelling of 639626 in words is "six hundred thirty-nine thousand, six hundred twenty-six".