77780081 has 2 divisors, whose sum is σ = 77780082. Its totient is φ = 77780080.

The previous prime is 77780057. The next prime is 77780093. The reversal of 77780081 is 18008777.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69889600 + 7890481 = 8360^2 + 2809^2 .

It is an emirp because it is prime and its reverse (18008777) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77780081 - 2¹⁰ = 77779057 is a prime.

It is a super-2 number, since 2×77780081² = 12099482000733122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77780041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38890040 + 38890041.

It is an arithmetic number, because the mean of its divisors is an integer number (38890041).

Almost surely, 2^77780081 is an apocalyptic number.

It is an amenable number.

77780081 is a deficient number, since it is larger than the sum of its proper divisors (1).

77780081 is an equidigital number, since it uses as much as digits as its factorization.

77780081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21952, while the sum is 38.

The square root of 77780081 is about 8819.3016163413. The cubic root of 77780081 is about 426.8639351329.

The spelling of 77780081 in words is "seventy-seven million, seven hundred eighty thousand, eighty-one".