7881638 has 8 divisors (see below), whose sum is σ = 11944632. Its totient is φ = 3900096.

The previous prime is 7881619. The next prime is 7881647. The reversal of 7881638 is 8361887.

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

It is a junction number, because it is equal to n+sod(n) for n = 7881595 and 7881604.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 20120 + ... + 20507.

It is an arithmetic number, because the mean of its divisors is an integer number (1493079).

Almost surely, 2^7881638 is an apocalyptic number.

7881638 is a deficient number, since it is larger than the sum of its proper divisors (4062994).

7881638 is a wasteful number, since it uses less digits than its factorization.

7881638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40726.

The product of its digits is 64512, while the sum is 41.

The square root of 7881638 is about 2807.4255110332. The cubic root of 7881638 is about 199.0087451861.

Subtracting 7881638 from its reverse (8361887), we obtain a square (480249 = 693²).

The spelling of 7881638 in words is "seven million, eight hundred eighty-one thousand, six hundred thirty-eight".