77861517931 has 4 divisors (see below), whose sum is σ = 77902738200. Its totient is φ = 77820297664.

The previous prime is 77861517911. The next prime is 77861517953. The reversal of 77861517931 is 13971516877.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13971516877 = 6917 ⋅2019881.

It is a cyclic number.

It is not a de Polignac number, because 77861517931 - 2⁷ = 77861517803 is a prime.

It is a super-2 number, since 2×77861517931² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77861517911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20607301 + ... + 20611078.

It is an arithmetic number, because the mean of its divisors is an integer number (19475684550).

Almost surely, 2^77861517931 is an apocalyptic number.

77861517931 is a deficient number, since it is larger than the sum of its proper divisors (41220269).

77861517931 is a wasteful number, since it uses less digits than its factorization.

77861517931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41220268.

The product of its digits is 2222640, while the sum is 55.

The spelling of 77861517931 in words is "seventy-seven billion, eight hundred sixty-one million, five hundred seventeen thousand, nine hundred thirty-one".