77881970581 has 2 divisors, whose sum is σ = 77881970582. Its totient is φ = 77881970580.

The previous prime is 77881970567. The next prime is 77881970603. The reversal of 77881970581 is 18507918877.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72989667556 + 4892303025 = 270166^2 + 69945^2 .

It is a cyclic number.

It is not a de Polignac number, because 77881970581 - 2¹¹ = 77881968533 is a prime.

It is a super-2 number, since 2×77881970581² (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 (77881970381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38940985290 + 38940985291.

It is an arithmetic number, because the mean of its divisors is an integer number (38940985291).

Almost surely, 2^77881970581 is an apocalyptic number.

It is an amenable number.

77881970581 is a deficient number, since it is larger than the sum of its proper divisors (1).

77881970581 is an equidigital number, since it uses as much as digits as its factorization.

77881970581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7902720, while the sum is 61.

The spelling of 77881970581 in words is "seventy-seven billion, eight hundred eighty-one million, nine hundred seventy thousand, five hundred eighty-one".