7638991994 has 4 divisors (see below), whose sum is σ = 11458487994. Its totient is φ = 3819495996.

The previous prime is 7638991967. The next prime is 7638992021. The reversal of 7638991994 is 4991998367.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 4991998367 = 307 ⋅16260581.

It is an interprime number because it is at equal distance from previous prime (7638991967) and next prime (7638992021).

It can be written as a sum of positive squares in only one way, i.e., 6383211025 + 1255780969 = 79895^2 + 35437^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 7638991994.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1909747997 + ... + 1909748000.

Almost surely, 2^7638991994 is an apocalyptic number.

7638991994 is a deficient number, since it is larger than the sum of its proper divisors (3819496000).

7638991994 is a wasteful number, since it uses less digits than its factorization.

7638991994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3819495999.

The product of its digits is 26453952, while the sum is 65.

The square root of 7638991994 is about 87401.3271867195. The cubic root of 7638991994 is about 1969.4517781899.

The spelling of 7638991994 in words is "seven billion, six hundred thirty-eight million, nine hundred ninety-one thousand, nine hundred ninety-four".