8787780007561 has 9 divisors (see below), whose sum is σ = 8837681661543. Its totient is φ = 8738158597920.

The previous prime is 8787780007493. The next prime is 8787780007639. The reversal of 8787780007561 is 1657000877878.

The square root of 8787780007561 is 2964419.

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

It can be written as a sum of positive squares in only one way, i.e., 378939967561 + 8408840040000 = 615581^2 + 2899800^2 .

It is not a de Polignac number, because 8787780007561 - 2¹⁵ = 8787779974793 is a prime.

It is a super-2 number, since 2×8787780007561² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 8787780007493 and 8787780007502.

It is not an unprimeable number, because it can be changed into a prime (8787780007661) 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, 530622721 + ... + 530639281.

Almost surely, 2^{8787780007561} is an apocalyptic number.

8787780007561 is the 2964419-th square number.

8787780007561 is the 1482210-th centered octagonal number.

It is an amenable number.

8787780007561 is a deficient number, since it is larger than the sum of its proper divisors (49901653982).

8787780007561 is an frugal number, since it uses more digits than its factorization.

8787780007561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33480 (or 16740 counting only the distinct ones).

The product of its (nonzero) digits is 36879360, while the sum is 64.

Multiplying 8787780007561 by its sum of digits (64), we get a square (562417920483904 = 23715352²).

The spelling of 8787780007561 in words is "eight trillion, seven hundred eighty-seven billion, seven hundred eighty million, seven thousand, five hundred sixty-one".