81440811 has 12 divisors (see below), whose sum is σ = 120816592. Its totient is φ = 52826256.

The previous prime is 81440809. The next prime is 81440819. The reversal of 81440811 is 11804418.

It is not a de Polignac number, because 81440811 - 2¹ = 81440809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81440819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 121951 + ... + 122616.

Almost surely, 2^81440811 is an apocalyptic number.

81440811 is a deficient number, since it is larger than the sum of its proper divisors (39375781).

81440811 is a wasteful number, since it uses less digits than its factorization.

81440811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244610 (or 244607 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 27.

The square root of 81440811 is about 9024.4562717097. The cubic root of 81440811 is about 433.4583398062.

The spelling of 81440811 in words is "eighty-one million, four hundred forty thousand, eight hundred eleven".