77878250581 has 2 divisors, whose sum is σ = 77878250582. Its totient is φ = 77878250580.

The previous prime is 77878250573. The next prime is 77878250603. The reversal of 77878250581 is 18505287877.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42573719556 + 35304531025 = 206334^2 + 187895^2 .

It is a cyclic number.

It is not a de Polignac number, because 77878250581 - 2³ = 77878250573 is a prime.

It is a super-2 number, since 2×77878250581² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77878250521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38939125290 + 38939125291.

It is an arithmetic number, because the mean of its divisors is an integer number (38939125291).

Almost surely, 2^77878250581 is an apocalyptic number.

It is an amenable number.

77878250581 is a deficient number, since it is larger than the sum of its proper divisors (1).

77878250581 is an equidigital number, since it uses as much as digits as its factorization.

77878250581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8780800, while the sum is 58.

The spelling of 77878250581 in words is "seventy-seven billion, eight hundred seventy-eight million, two hundred fifty thousand, five hundred eighty-one".