1028310805721 has 4 divisors (see below), whose sum is σ = 1029648011700. Its totient is φ = 1026973599744.

The previous prime is 1028310805619. The next prime is 1028310805727. The reversal of 1028310805721 is 1275080138201.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 130365045721 + 897945760000 = 361061^2 + 947600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1028310805721 is a prime.

It is a super-2 number, since 2×1028310805721² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1028310805727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 668601836 + ... + 668603373.

It is an arithmetic number, because the mean of its divisors is an integer number (257412002925).

Almost surely, 2^{1028310805721} is an apocalyptic number.

It is an amenable number.

1028310805721 is a deficient number, since it is larger than the sum of its proper divisors (1337205979).

1028310805721 is an equidigital number, since it uses as much as digits as its factorization.

1028310805721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1337205978.

The product of its (nonzero) digits is 26880, while the sum is 38.

The spelling of 1028310805721 in words is "one trillion, twenty-eight billion, three hundred ten million, eight hundred five thousand, seven hundred twenty-one".