1980728865 has 24 divisors (see below), whose sum is σ = 3489551208. Its totient is φ = 1039069440.

The previous prime is 1980728863. The next prime is 1980728873. The reversal of 1980728865 is 5688270891.

It can be written as a sum of positive squares in 4 ways, for example, as 141348321 + 1839380544 = 11889^2 + 42888^2 .

It is not a de Polignac number, because 1980728865 - 2¹ = 1980728863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1980728863) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 358044 + ... + 363533.

It is an arithmetic number, because the mean of its divisors is an integer number (145397967).

Almost surely, 2^1980728865 is an apocalyptic number.

1980728865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1980728865 is a deficient number, since it is larger than the sum of its proper divisors (1508822343).

1980728865 is a wasteful number, since it uses less digits than its factorization.

1980728865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721649 (or 721646 counting only the distinct ones).

The product of its (nonzero) digits is 1935360, while the sum is 54.

The square root of 1980728865 is about 44505.3801803782. The cubic root of 1980728865 is about 1255.8612977269.

The spelling of 1980728865 in words is "one billion, nine hundred eighty million, seven hundred twenty-eight thousand, eight hundred sixty-five".