787372561721 has 4 divisors (see below), whose sum is σ = 789396656100. Its totient is φ = 785348467344.

The previous prime is 787372561711. The next prime is 787372561733. The reversal of 787372561721 is 127165273787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127165273787 = 67 ⋅1897989161.

It can be written as a sum of positive squares in 2 ways, for example, as 496511892496 + 290860669225 = 704636^2 + 539315^2 .

It is a cyclic number.

It is not a de Polignac number, because 787372561721 - 2³⁴ = 770192692537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (787372561711) 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, 1012046606 + ... + 1012047383.

It is an arithmetic number, because the mean of its divisors is an integer number (197349164025).

Almost surely, 2^787372561721 is an apocalyptic number.

It is an amenable number.

787372561721 is a deficient number, since it is larger than the sum of its proper divisors (2024094379).

787372561721 is a wasteful number, since it uses less digits than its factorization.

787372561721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2024094378.

The product of its digits is 6914880, while the sum is 56.

The spelling of 787372561721 in words is "seven hundred eighty-seven billion, three hundred seventy-two million, five hundred sixty-one thousand, seven hundred twenty-one".