3128260778721 has 63 divisors (see below), whose sum is σ = 5079794734659. Its totient is φ = 1924701519312.

The previous prime is 3128260778719. The next prime is 3128260778723. The reversal of 3128260778721 is 1278770628213.

The square root of 3128260778721 is 1768689.

It is a perfect power (a square), and thus also a powerful number.

3128260778721 is a `hidden beast` number, since 3 + 1 + 2 + 8 + 2 + 607 + 7 + 8 + 7 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (3128260778719) and next prime (3128260778723).

It can be written as a sum of positive squares in only one way, i.e., 462760470225 + 2665500308496 = 680265^2 + 1632636^2 .

It is not a de Polignac number, because 3128260778721 - 2¹ = 3128260778719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3128260778723) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 620807320 + ... + 620812358.

Almost surely, 2^{3128260778721} is an apocalyptic number.

3128260778721 is the 1768689-th square number.

3128260778721 is the 884345-th centered octagonal number.

It is an amenable number.

3128260778721 is a deficient number, since it is larger than the sum of its proper divisors (1951533955938).

3128260778721 is an frugal number, since it uses more digits than its factorization.

3128260778721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10122 (or 5055 counting only the distinct ones).

The product of its (nonzero) digits is 3161088, while the sum is 54.

The spelling of 3128260778721 in words is "three trillion, one hundred twenty-eight billion, two hundred sixty million, seven hundred seventy-eight thousand, seven hundred twenty-one".