638261 has 8 divisors (see below), whose sum is σ = 711480. Its totient is φ = 568512.

The previous prime is 638233. The next prime is 638263. The reversal of 638261 is 162836.

638261 = T₇₅ + T₇₆ + ... + T₁₆₁.

638261 = 144² + 145² + ... + 169².

It can be written as a sum of positive squares in 4 ways, for example, as 14161 + 624100 = 119^2 + 790^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638261 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638263) 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, 470 + ... + 1223.

It is an arithmetic number, because the mean of its divisors is an integer number (88935).

2⁶³⁸²⁶¹ is an apocalyptic number.

It is an amenable number.

638261 is a deficient number, since it is larger than the sum of its proper divisors (73219).

638261 is a wasteful number, since it uses less digits than its factorization.

638261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735.

The product of its digits is 1728, while the sum is 26.

The square root of 638261 is about 798.9123856844. The cubic root of 638261 is about 86.0992634257.

The spelling of 638261 in words is "six hundred thirty-eight thousand, two hundred sixty-one".