81776247 has 72 divisors (see below), whose sum is σ = 141768576. Its totient is φ = 41713056.

The previous prime is 81776237. The next prime is 81776249. The reversal of 81776247 is 74267718.

It is not a de Polignac number, because 81776247 - 2¹⁵ = 81743479 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81776199 and 81776208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81776249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1220508 + ... + 1220574.

It is an arithmetic number, because the mean of its divisors is an integer number (1969008).

Almost surely, 2^81776247 is an apocalyptic number.

81776247 is a deficient number, since it is larger than the sum of its proper divisors (59992329).

81776247 is a wasteful number, since it uses less digits than its factorization.

81776247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 119 counting only the distinct ones).

The product of its digits is 131712, while the sum is 42.

The square root of 81776247 is about 9043.0220059447. The cubic root of 81776247 is about 434.0526297604.

The spelling of 81776247 in words is "eighty-one million, seven hundred seventy-six thousand, two hundred forty-seven".