81805451 has 24 divisors (see below), whose sum is σ = 103229280. Its totient is φ = 64253952.

The previous prime is 81805429. The next prime is 81805487. The reversal of 81805451 is 15450818.

It is not a de Polignac number, because 81805451 - 2⁶ = 81805387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81805351) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 105995 + ... + 106763.

It is an arithmetic number, because the mean of its divisors is an integer number (4301220).

Almost surely, 2^81805451 is an apocalyptic number.

81805451 is a deficient number, since it is larger than the sum of its proper divisors (21423829).

81805451 is a wasteful number, since it uses less digits than its factorization.

81805451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 963 (or 956 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 32.

The square root of 81805451 is about 9044.6365875031. The cubic root of 81805451 is about 434.1042933539.

It can be divided in two parts, 8180 and 5451, that added together give a palindrome (13631).

The spelling of 81805451 in words is "eighty-one million, eight hundred five thousand, four hundred fifty-one".