638769 has 4 divisors (see below), whose sum is σ = 851696. Its totient is φ = 425844.

The previous prime is 638767. The next prime is 638801. The reversal of 638769 is 967836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 638769 - 2¹ = 638767 is a prime.

It is a super-2 number, since 2×638769² = 816051670722, which contains 22 as substring.

It is a D-number.

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

It is a Duffinian number.

638769 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 638769.

It is not an unprimeable number, because it can be changed into a prime (638767) 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, 106459 + ... + 106464.

It is an arithmetic number, because the mean of its divisors is an integer number (212924).

2⁶³⁸⁷⁶⁹ is an apocalyptic number.

It is an amenable number.

638769 is a deficient number, since it is larger than the sum of its proper divisors (212927).

638769 is a wasteful number, since it uses less digits than its factorization.

638769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212926.

The product of its digits is 54432, while the sum is 39.

The square root of 638769 is about 799.2302546826. The cubic root of 638769 is about 86.1220998656.

The spelling of 638769 in words is "six hundred thirty-eight thousand, seven hundred sixty-nine".