81401805 has 24 divisors (see below), whose sum is σ = 141397152. Its totient is φ = 43321824.

The previous prime is 81401783. The next prime is 81401809. The reversal of 81401805 is 50810418.

It is not a de Polignac number, because 81401805 - 2⁶ = 81401741 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81401809) 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, 22962 + ... + 26268.

It is an arithmetic number, because the mean of its divisors is an integer number (5891548).

Almost surely, 2^81401805 is an apocalyptic number.

It is an amenable number.

81401805 is a deficient number, since it is larger than the sum of its proper divisors (59995347).

81401805 is a wasteful number, since it uses less digits than its factorization.

81401805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3865 (or 3862 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 81401805 is about 9022.2948854490. The cubic root of 81401805 is about 433.3891272669.

The spelling of 81401805 in words is "eighty-one million, four hundred one thousand, eight hundred five".