1978880986 has 4 divisors (see below), whose sum is σ = 2968321482. Its totient is φ = 989440492.

The previous prime is 1978880947. The next prime is 1978880987. The reversal of 1978880986 is 6890888791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6890888791 = 193 ⋅35704087.

It can be written as a sum of positive squares in only one way, i.e., 1964173761 + 14707225 = 44319^2 + 3835^2 .

It is not an unprimeable number, because it can be changed into a prime (1978880987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494720245 + ... + 494720248.

Almost surely, 2^1978880986 is an apocalyptic number.

1978880986 is a deficient number, since it is larger than the sum of its proper divisors (989440496).

1978880986 is an equidigital number, since it uses as much as digits as its factorization.

1978880986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 989440495.

The product of its (nonzero) digits is 13934592, while the sum is 64.

The square root of 1978880986 is about 44484.6151607497. The cubic root of 1978880986 is about 1255.4706331571.

The spelling of 1978880986 in words is "one billion, nine hundred seventy-eight million, eight hundred eighty thousand, nine hundred eighty-six".