77131391 has 4 divisors (see below), whose sum is σ = 77237352. Its totient is φ = 77025432.

The previous prime is 77131361. The next prime is 77131403. The reversal of 77131391 is 19313177.

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 77131391 - 2²² = 72937087 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77131321) 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, 51881 + ... + 53346.

It is an arithmetic number, because the mean of its divisors is an integer number (19309338).

Almost surely, 2^77131391 is an apocalyptic number.

77131391 is a deficient number, since it is larger than the sum of its proper divisors (105961).

77131391 is a wasteful number, since it uses less digits than its factorization.

77131391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105960.

The product of its digits is 3969, while the sum is 32.

The square root of 77131391 is about 8782.4478933837. The cubic root of 77131391 is about 425.6739314598.

The spelling of 77131391 in words is "seventy-seven million, one hundred thirty-one thousand, three hundred ninety-one".