778728061 has 4 divisors (see below), whose sum is σ = 824535612. Its totient is φ = 732920512.

The previous prime is 778728019. The next prime is 778728073. The reversal of 778728061 is 160827877.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 213715161 + 565012900 = 14619^2 + 23770^2 .

It is a cyclic number.

It is not a de Polignac number, because 778728061 - 2⁷ = 778727933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (778725061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22903750 + ... + 22903783.

It is an arithmetic number, because the mean of its divisors is an integer number (206133903).

Almost surely, 2^778728061 is an apocalyptic number.

It is an amenable number.

778728061 is a deficient number, since it is larger than the sum of its proper divisors (45807551).

778728061 is a wasteful number, since it uses less digits than its factorization.

778728061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45807550.

The product of its (nonzero) digits is 263424, while the sum is 46.

The square root of 778728061 is about 27905.6994357783. The cubic root of 778728061 is about 920.0157767458.

The spelling of 778728061 in words is "seven hundred seventy-eight million, seven hundred twenty-eight thousand, sixty-one".