77781305449 has 27 divisors (see below), whose sum is σ = 82450212663. Its totient is φ = 73373401584.

The previous prime is 77781305411. The next prime is 77781305489. The reversal of 77781305449 is 94450318777.

The square root of 77781305449 is 278893.

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., 40786629849 + 36994675600 = 201957^2 + 192340^2 .

It is not a de Polignac number, because 77781305449 - 2²⁹ = 77244434537 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77781305449.

It is not an unprimeable number, because it can be changed into a prime (77781305489) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 477185842 + ... + 477186004.

Almost surely, 2^77781305449 is an apocalyptic number.

77781305449 is the 278893-rd square number.

77781305449 is the 139447-th centered octagonal number.

It is an amenable number.

77781305449 is a deficient number, since it is larger than the sum of its proper divisors (4668907214).

77781305449 is an frugal number, since it uses more digits than its factorization.

77781305449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 5927040, while the sum is 55.

The spelling of 77781305449 in words is "seventy-seven billion, seven hundred eighty-one million, three hundred five thousand, four hundred forty-nine".