77728009689801 has 9 divisors (see below), whose sum is σ = 112273829978349. Its totient is φ = 51818655493836.

The previous prime is 77728009689727. The next prime is 77728009689833. The reversal of 77728009689801 is 10898690082777.

The square root of 77728009689801 is 8816349.

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 77728009689801 - 2²³ = 77728001301193 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 77728009689801.

It is not an unprimeable number, because it can be changed into a prime (77728009681801) 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, 24979656 + ... + 27918438.

Almost surely, 2^{77728009689801} is an apocalyptic number.

77728009689801 is the 8816349-th square number.

77728009689801 is the 4408175-th centered octagonal number.

It is an amenable number.

77728009689801 is a deficient number, since it is larger than the sum of its proper divisors (34545820288548).

77728009689801 is an frugal number, since it uses more digits than its factorization.

77728009689801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5877572 (or 2938786 counting only the distinct ones).

The product of its (nonzero) digits is 170698752, while the sum is 72.

The spelling of 77728009689801 in words is "seventy-seven trillion, seven hundred twenty-eight billion, nine million, six hundred eighty-nine thousand, eight hundred one".