638949 has 8 divisors (see below), whose sum is σ = 855712. Its totient is φ = 424080.

The previous prime is 638933. The next prime is 638959. The reversal of 638949 is 949836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 638949 - 2⁴ = 638933 is a prime.

It is an Ulam number.

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

It is a Duffinian number.

638949 is a lucky number.

It is a congruent 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 7 ways as a sum of consecutive naturals, for example, 834 + ... + 1404.

It is an arithmetic number, because the mean of its divisors is an integer number (106964).

2⁶³⁸⁹⁴⁹ is an apocalyptic number.

It is an amenable number.

638949 is a deficient number, since it is larger than the sum of its proper divisors (216763).

638949 is a wasteful number, since it uses less digits than its factorization.

638949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947.

The product of its digits is 46656, while the sum is 39.

The square root of 638949 is about 799.3428551004. The cubic root of 638949 is about 86.1301886124.

It can be divided in two parts, 63894 and 9, that added together give a triangular number (63903 = T₃₅₇).

The spelling of 638949 in words is "six hundred thirty-eight thousand, nine hundred forty-nine".