77380781 has 4 divisors (see below), whose sum is σ = 77660412. Its totient is φ = 77101152.

The previous prime is 77380739. The next prime is 77380813. The reversal of 77380781 is 18708377.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25050025 + 52330756 = 5005^2 + 7234^2 .

It is a cyclic number.

It is not a de Polignac number, because 77380781 - 2¹⁸ = 77118637 is a prime.

It is a super-2 number, since 2×77380781² = 11975570536339922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77380181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139400 + ... + 139953.

It is an arithmetic number, because the mean of its divisors is an integer number (19415103).

Almost surely, 2^77380781 is an apocalyptic number.

It is an amenable number.

77380781 is a deficient number, since it is larger than the sum of its proper divisors (279631).

77380781 is a wasteful number, since it uses less digits than its factorization.

77380781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279630.

The product of its (nonzero) digits is 65856, while the sum is 41.

The square root of 77380781 is about 8796.6346405884. The cubic root of 77380781 is about 426.1322170361.

The spelling of 77380781 in words is "seventy-seven million, three hundred eighty thousand, seven hundred eighty-one".