639551 has 8 divisors (see below), whose sum is σ = 711504. Its totient is φ = 569920.

The previous prime is 639547. The next prime is 639563. The reversal of 639551 is 155936.

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

It is a cyclic number.

It is not a de Polignac number, because 639551 - 2² = 639547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639551.

It is not an unprimeable number, because it can be changed into a prime (639511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35 + ... + 1131.

It is an arithmetic number, because the mean of its divisors is an integer number (88938).

2⁶³⁹⁵⁵¹ is an apocalyptic number.

639551 is a deficient number, since it is larger than the sum of its proper divisors (71953).

639551 is a wasteful number, since it uses less digits than its factorization.

639551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1161.

The product of its digits is 4050, while the sum is 29.

The square root of 639551 is about 799.7193257637. The cubic root of 639551 is about 86.1572299454.

It can be divided in two parts, 6395 and 51, that added together give a palindrome (6446).

The spelling of 639551 in words is "six hundred thirty-nine thousand, five hundred fifty-one".