5121778561 has 4 divisors (see below), whose sum is σ = 5140818900. Its totient is φ = 5102738224.

The previous prime is 5121778559. The next prime is 5121778573. The reversal of 5121778561 is 1658771215.

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 989731600 + 4132046961 = 31460^2 + 64281^2 .

It is a cyclic number.

It is not a de Polignac number, because 5121778561 - 2¹ = 5121778559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (5121778511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9519766 + ... + 9520303.

It is an arithmetic number, because the mean of its divisors is an integer number (1285204725).

Almost surely, 2^5121778561 is an apocalyptic number.

It is an amenable number.

5121778561 is a deficient number, since it is larger than the sum of its proper divisors (19040339).

5121778561 is a wasteful number, since it uses less digits than its factorization.

5121778561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19040338.

The product of its digits is 117600, while the sum is 43.

The square root of 5121778561 is about 71566.6022736863. The cubic root of 5121778561 is about 1723.7473015001.

The spelling of 5121778561 in words is "five billion, one hundred twenty-one million, seven hundred seventy-eight thousand, five hundred sixty-one".