7899855638 has 4 divisors (see below), whose sum is σ = 11849783460. Its totient is φ = 3949927818.

The previous prime is 7899855619. The next prime is 7899855697. The reversal of 7899855638 is 8365589987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8365589987 = 1319 ⋅6342373.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1974963908 + ... + 1974963911.

It is an arithmetic number, because the mean of its divisors is an integer number (2962445865).

Almost surely, 2^7899855638 is an apocalyptic number.

7899855638 is a deficient number, since it is larger than the sum of its proper divisors (3949927822).

7899855638 is a wasteful number, since it uses less digits than its factorization.

7899855638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3949927821.

The product of its digits is 130636800, while the sum is 68.

The square root of 7899855638 is about 88881.1320697481. The cubic root of 7899855638 is about 1991.6195697419.

The spelling of 7899855638 in words is "seven billion, eight hundred ninety-nine million, eight hundred fifty-five thousand, six hundred thirty-eight".