77899891 has 2 divisors, whose sum is σ = 77899892. Its totient is φ = 77899890.

The previous prime is 77899889. The next prime is 77899903. The reversal of 77899891 is 19899877.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 77899891 - 2¹ = 77899889 is a prime.

Together with 77899889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (77899391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38949945 + 38949946.

It is an arithmetic number, because the mean of its divisors is an integer number (38949946).

Almost surely, 2^77899891 is an apocalyptic number.

77899891 is a deficient number, since it is larger than the sum of its proper divisors (1).

77899891 is an equidigital number, since it uses as much as digits as its factorization.

77899891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2286144, while the sum is 58.

The square root of 77899891 is about 8826.0914905750. The cubic root of 77899891 is about 427.0829986360.

The spelling of 77899891 in words is "seventy-seven million, eight hundred ninety-nine thousand, eight hundred ninety-one".