81776249 has 2 divisors, whose sum is σ = 81776250. Its totient is φ = 81776248.

The previous prime is 81776237. The next prime is 81776281. The reversal of 81776249 is 94267718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81775849 + 400 = 9043^2 + 20^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81776249 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81773249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40888124 + 40888125.

It is an arithmetic number, because the mean of its divisors is an integer number (40888125).

Almost surely, 2^81776249 is an apocalyptic number.

It is an amenable number.

81776249 is a deficient number, since it is larger than the sum of its proper divisors (1).

81776249 is an equidigital number, since it uses as much as digits as its factorization.

81776249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 44.

The square root of 81776249 is about 9043.0221165272. The cubic root of 81776249 is about 434.0526332989.

The spelling of 81776249 in words is "eighty-one million, seven hundred seventy-six thousand, two hundred forty-nine".