1978880985 has 12 divisors (see below), whose sum is σ = 3430060452. Its totient is φ = 1055403168.

The previous prime is 1978880947. The next prime is 1978880987. The reversal of 1978880985 is 5890888791.

It can be written as a sum of positive squares in 2 ways, for example, as 1280494656 + 698386329 = 35784^2 + 26427^2 .

It is not a de Polignac number, because 1978880985 - 2¹³ = 1978872793 is a prime.

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 in 11 ways as a sum of consecutive naturals, for example, 21987522 + ... + 21987611.

It is an arithmetic number, because the mean of its divisors is an integer number (285838371).

Almost surely, 2^1978880985 is an apocalyptic number.

1978880985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1978880985 is a deficient number, since it is larger than the sum of its proper divisors (1451179467).

1978880985 is a wasteful number, since it uses less digits than its factorization.

1978880985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43975144 (or 43975141 counting only the distinct ones).

The product of its (nonzero) digits is 11612160, while the sum is 63.

The square root of 1978880985 is about 44484.6151495098. The cubic root of 1978880985 is about 1255.4706329457.

The spelling of 1978880985 in words is "one billion, nine hundred seventy-eight million, eight hundred eighty thousand, nine hundred eighty-five".