778061720531 has 4 divisors (see below), whose sum is σ = 796156179192. Its totient is φ = 759967261872.

The previous prime is 778061720507. The next prime is 778061720543. The reversal of 778061720531 is 135027160877.

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

It is a cyclic number.

It is not a de Polignac number, because 778061720531 - 2²² = 778057526227 is a prime.

It is a super-2 number, since 2×778061720531² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (778061720231) 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, 9047229266 + ... + 9047229351.

It is an arithmetic number, because the mean of its divisors is an integer number (199039044798).

Almost surely, 2^778061720531 is an apocalyptic number.

778061720531 is a deficient number, since it is larger than the sum of its proper divisors (18094458661).

778061720531 is a wasteful number, since it uses less digits than its factorization.

778061720531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18094458660.

The product of its (nonzero) digits is 493920, while the sum is 47.

The spelling of 778061720531 in words is "seven hundred seventy-eight billion, sixty-one million, seven hundred twenty thousand, five hundred thirty-one".