778120551 has 12 divisors (see below), whose sum is σ = 1210409928. Its totient is φ = 478843344.

The previous prime is 778120529. The next prime is 778120559. The reversal of 778120551 is 155021877.

778120551 is a `hidden beast` number, since 7 + 7 + 81 + 20 + 551 = 666.

It is not a de Polignac number, because 778120551 - 2⁶ = 778120487 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (778120559) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3325185 + ... + 3325418.

It is an arithmetic number, because the mean of its divisors is an integer number (100867494).

Almost surely, 2^778120551 is an apocalyptic number.

778120551 is a deficient number, since it is larger than the sum of its proper divisors (432289377).

778120551 is a wasteful number, since it uses less digits than its factorization.

778120551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6650622 (or 6650619 counting only the distinct ones).

The product of its (nonzero) digits is 19600, while the sum is 36.

The square root of 778120551 is about 27894.8122596299. The cubic root of 778120551 is about 919.7764701899.

The spelling of 778120551 in words is "seven hundred seventy-eight million, one hundred twenty thousand, five hundred fifty-one".