771720280128 has 126 divisors (see below), whose sum is σ = 2573139280686. Its totient is φ = 220491500544.

The previous prime is 771720280127. The next prime is 771720280229. The reversal of 771720280128 is 821082027177.

It can be written as a sum of positive squares in only one way, i.e., 771713054784 + 7225344 = 878472^2 + 2688^2 .

It is a tau number, because it is divible by the number of its divisors (126).

It is not an unprimeable number, because it can be changed into a prime (771720280127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 13643125 + ... + 13699572.

Almost surely, 2^771720280128 is an apocalyptic number.

It is an amenable number.

771720280128 is an abundant number, since it is smaller than the sum of its proper divisors (1801419000558).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

771720280128 is a wasteful number, since it uses less digits than its factorization.

771720280128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27342729 (or 27342709 counting only the distinct ones).

The product of its (nonzero) digits is 175616, while the sum is 45.

The spelling of 771720280128 in words is "seven hundred seventy-one billion, seven hundred twenty million, two hundred eighty thousand, one hundred twenty-eight".