638252786 has 4 divisors (see below), whose sum is σ = 957379182. Its totient is φ = 319126392.

The previous prime is 638252779. The next prime is 638252801. The reversal of 638252786 is 687252836.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 633478561 + 4774225 = 25169^2 + 2185^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 638252786.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159563195 + ... + 159563198.

Almost surely, 2^638252786 is an apocalyptic number.

638252786 is a deficient number, since it is larger than the sum of its proper divisors (319126396).

638252786 is a wasteful number, since it uses less digits than its factorization.

638252786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319126395.

The product of its digits is 967680, while the sum is 47.

The square root of 638252786 is about 25263.6653318556. The cubic root of 638252786 is about 860.9889407711.

Subtracting 638252786 from its reverse (687252836), we obtain a triangular number (49000050 = T₉₈₉₉).

The spelling of 638252786 in words is "six hundred thirty-eight million, two hundred fifty-two thousand, seven hundred eighty-six".