81249999977 has 2 divisors, whose sum is σ = 81249999978. Its totient is φ = 81249999976.

The previous prime is 81249999949. The next prime is 81250000199. The reversal of 81249999977 is 77999994218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63639648361 + 17610351616 = 252269^2 + 132704^2 .

It is a cyclic number.

It is not a de Polignac number, because 81249999977 - 2¹⁴ = 81249983593 is a prime.

It is not a weakly prime, because it can be changed into another prime (81249999577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40624999988 + 40624999989.

It is an arithmetic number, because the mean of its divisors is an integer number (40624999989).

Almost surely, 2^81249999977 is an apocalyptic number.

It is an amenable number.

81249999977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81249999977 is an equidigital number, since it uses as much as digits as its factorization.

81249999977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 185177664, while the sum is 74.

The spelling of 81249999977 in words is "eighty-one billion, two hundred forty-nine million, nine hundred ninety-nine thousand, nine hundred seventy-seven".