81493777 has 2 divisors, whose sum is σ = 81493778. Its totient is φ = 81493776.

The previous prime is 81493751. The next prime is 81493781. The reversal of 81493777 is 77739418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73205136 + 8288641 = 8556^2 + 2879^2 .

It is a cyclic number.

It is not a de Polignac number, because 81493777 - 2²³ = 73105169 is a prime.

It is not a weakly prime, because it can be changed into another prime (81493877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40746888 + 40746889.

It is an arithmetic number, because the mean of its divisors is an integer number (40746889).

Almost surely, 2^81493777 is an apocalyptic number.

It is an amenable number.

81493777 is a deficient number, since it is larger than the sum of its proper divisors (1).

81493777 is an equidigital number, since it uses as much as digits as its factorization.

81493777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 296352, while the sum is 46.

The square root of 81493777 is about 9027.3903759614. The cubic root of 81493777 is about 433.5522877046.

The spelling of 81493777 in words is "eighty-one million, four hundred ninety-three thousand, seven hundred seventy-seven".