781672120321 has 4 divisors (see below), whose sum is σ = 784169475652. Its totient is φ = 779174764992.

The previous prime is 781672120301. The next prime is 781672120331. The reversal of 781672120321 is 123021276187.

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 346420530625 + 435251589696 = 588575^2 + 659736^2 .

It is a cyclic number.

It is not a de Polignac number, because 781672120321 - 2¹¹ = 781672118273 is a prime.

It is a super-2 number, since 2×781672120321² (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 (781672120301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1248677196 + ... + 1248677821.

It is an arithmetic number, because the mean of its divisors is an integer number (196042368913).

Almost surely, 2^781672120321 is an apocalyptic number.

It is an amenable number.

781672120321 is a deficient number, since it is larger than the sum of its proper divisors (2497355331).

781672120321 is a wasteful number, since it uses less digits than its factorization.

781672120321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2497355330.

The product of its (nonzero) digits is 56448, while the sum is 40.

The spelling of 781672120321 in words is "seven hundred eighty-one billion, six hundred seventy-two million, one hundred twenty thousand, three hundred twenty-one".