7899639778 has 8 divisors (see below), whose sum is σ = 11854009260. Its totient is φ = 3948303360.

The previous prime is 7899639721. The next prime is 7899639793. The reversal of 7899639778 is 8779369987.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6881200209 + 1018439569 = 82953^2 + 31913^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 7899639778.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 751743 + ... + 762178.

Almost surely, 2^7899639778 is an apocalyptic number.

7899639778 is a deficient number, since it is larger than the sum of its proper divisors (3954369482).

7899639778 is a wasteful number, since it uses less digits than its factorization.

7899639778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1516532.

The product of its digits is 288054144, while the sum is 73.

The square root of 7899639778 is about 88879.9177429862. The cubic root of 7899639778 is about 1991.6014295406.

The spelling of 7899639778 in words is "seven billion, eight hundred ninety-nine million, six hundred thirty-nine thousand, seven hundred seventy-eight".