81806401 has 8 divisors (see below), whose sum is σ = 83825280. Its totient is φ = 79805232.

The previous prime is 81806393. The next prime is 81806447. The reversal of 81806401 is 10460818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81806401 - 2³ = 81806393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81806401.

It is not an unprimeable number, because it can be changed into a prime (81806701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5176 + ... + 13798.

It is an arithmetic number, because the mean of its divisors is an integer number (10478160).

Almost surely, 2^81806401 is an apocalyptic number.

It is an amenable number.

81806401 is a deficient number, since it is larger than the sum of its proper divisors (2018879).

81806401 is a wasteful number, since it uses less digits than its factorization.

81806401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8855.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 81806401 is about 9044.6891046625. The cubic root of 81806401 is about 434.1059737532.

The spelling of 81806401 in words is "eighty-one million, eight hundred six thousand, four hundred one".