77820131 has 2 divisors, whose sum is σ = 77820132. Its totient is φ = 77820130.

The previous prime is 77820121. The next prime is 77820133. The reversal of 77820131 is 13102877.

It is a strong prime.

It is an emirp because it is prime and its reverse (13102877) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77820131 is a prime.

It is a super-2 number, since 2×77820131² = 12111945577714322, which contains 22 as substring.

Together with 77820133, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 77820094 and 77820103.

It is not a weakly prime, because it can be changed into another prime (77820133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38910065 + 38910066.

It is an arithmetic number, because the mean of its divisors is an integer number (38910066).

Almost surely, 2^77820131 is an apocalyptic number.

77820131 is a deficient number, since it is larger than the sum of its proper divisors (1).

77820131 is an equidigital number, since it uses as much as digits as its factorization.

77820131 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 77820131 is about 8821.5719120801. The cubic root of 77820131 is about 426.9371885371.

The spelling of 77820131 in words is "seventy-seven million, eight hundred twenty thousand, one hundred thirty-one".