81176021 has 2 divisors, whose sum is σ = 81176022. Its totient is φ = 81176020.

The previous prime is 81176009. The next prime is 81176027. The reversal of 81176021 is 12067118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53728900 + 27447121 = 7330^2 + 5239^2 .

It is a cyclic number.

It is not a de Polignac number, because 81176021 - 2¹⁰ = 81174997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81176027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40588010 + 40588011.

It is an arithmetic number, because the mean of its divisors is an integer number (40588011).

Almost surely, 2^81176021 is an apocalyptic number.

It is an amenable number.

81176021 is a deficient number, since it is larger than the sum of its proper divisors (1).

81176021 is an equidigital number, since it uses as much as digits as its factorization.

81176021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 81176021 is about 9009.7736375561. The cubic root of 81176021 is about 432.9880594147.

The spelling of 81176021 in words is "eighty-one million, one hundred seventy-six thousand, twenty-one".