77756027507561 has 16 divisors (see below), whose sum is σ = 88663462012944. Its totient is φ = 67552381845504.

The previous prime is 77756027507537. The next prime is 77756027507579. The reversal of 77756027507561 is 16570572065777.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 30533017897561 + 47223009610000 = 5525669^2 + 6871900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77756027507561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77756027506561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44905481 + ... + 46604873.

It is an arithmetic number, because the mean of its divisors is an integer number (5541466375809).

Almost surely, 2^{77756027507561} is an apocalyptic number.

It is an amenable number.

77756027507561 is a deficient number, since it is larger than the sum of its proper divisors (10907434505383).

77756027507561 is a wasteful number, since it uses less digits than its factorization.

77756027507561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1906460.

The product of its (nonzero) digits is 151263000, while the sum is 65.

The spelling of 77756027507561 in words is "seventy-seven trillion, seven hundred fifty-six billion, twenty-seven million, five hundred seven thousand, five hundred sixty-one".