638969 has 4 divisors (see below), whose sum is σ = 647796. Its totient is φ = 630144.

The previous prime is 638959. The next prime is 638971. The reversal of 638969 is 969836.

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 469225 + 169744 = 685^2 + 412^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638969 is a prime.

It is a super-2 number, since 2×638969² = 816562765922, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638959) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4304 + ... + 4449.

It is an arithmetic number, because the mean of its divisors is an integer number (161949).

2⁶³⁸⁹⁶⁹ is an apocalyptic number.

It is an amenable number.

638969 is a deficient number, since it is larger than the sum of its proper divisors (8827).

638969 is an equidigital number, since it uses as much as digits as its factorization.

638969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8826.

The product of its digits is 69984, while the sum is 41.

The square root of 638969 is about 799.3553652788. The cubic root of 638969 is about 86.1310872683.

The spelling of 638969 in words is "six hundred thirty-eight thousand, nine hundred sixty-nine".