7287780768921 has 9 divisors (see below), whose sum is σ = 10526806142229. Its totient is φ = 4858515113436.

The previous prime is 7287780768869. The next prime is 7287780768979. The reversal of 7287780768921 is 1298670877827.

The square root of 7287780768921 is 2699589.

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

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 7287780768921 - 2¹¹ = 7287780766873 is a prime.

It is a super-2 number, since 2×7287780768921² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 7287780768921.

It is not an unprimeable number, because it can be changed into a prime (7287780769921) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 7648836 + ... + 8548698.

Almost surely, 2^{7287780768921} is an apocalyptic number.

7287780768921 is the 2699589-th square number.

7287780768921 is the 1349795-th centered octagonal number.

It is an amenable number.

7287780768921 is a deficient number, since it is larger than the sum of its proper divisors (3239025373308).

7287780768921 is an frugal number, since it uses more digits than its factorization.

7287780768921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1799732 (or 899866 counting only the distinct ones).

The product of its (nonzero) digits is 265531392, while the sum is 72.

The spelling of 7287780768921 in words is "seven trillion, two hundred eighty-seven billion, seven hundred eighty million, seven hundred sixty-eight thousand, nine hundred twenty-one".