77811428809 has 3 divisors (see below), whose sum is σ = 77811707757. Its totient is φ = 77811149862.

The previous prime is 77811428789. The next prime is 77811428819. The reversal of 77811428809 is 90882411877.

The square root of 77811428809 is 278947.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a de Polignac number, because none of the positive numbers 2^k-77811428809 is a prime.

It is a super-3 number, since 3×77811428809³ (a number of 34 digits) contains 333 as substring.

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 77811428809.

It is not an unprimeable number, because it can be changed into a prime (77811428819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 139474 + ... + 418420.

It is an arithmetic number, because the mean of its divisors is an integer number (25937235919).

Almost surely, 2^77811428809 is an apocalyptic number.

77811428809 is the 278947-th square number.

77811428809 is the 139474-th centered octagonal number.

It is an amenable number.

77811428809 is a deficient number, since it is larger than the sum of its proper divisors (278948).

77811428809 is an frugal number, since it uses more digits than its factorization.

77811428809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557894 (or 278947 counting only the distinct ones).

The product of its (nonzero) digits is 1806336, while the sum is 55.

The spelling of 77811428809 in words is "seventy-seven billion, eight hundred eleven million, four hundred twenty-eight thousand, eight hundred nine".