81401855 has 16 divisors (see below), whose sum is σ = 100030464. Its totient is φ = 63574560.

The previous prime is 81401839. The next prime is 81401891. The reversal of 81401855 is 55810418.

It is not a de Polignac number, because 81401855 - 2⁴ = 81401839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36914 + ... + 39056.

It is an arithmetic number, because the mean of its divisors is an integer number (6251904).

Almost surely, 2^81401855 is an apocalyptic number.

81401855 is a deficient number, since it is larger than the sum of its proper divisors (18628609).

81401855 is a wasteful number, since it uses less digits than its factorization.

81401855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2326.

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

The square root of 81401855 is about 9022.2976563623. The cubic root of 81401855 is about 433.3892160015.

The spelling of 81401855 in words is "eighty-one million, four hundred one thousand, eight hundred fifty-five".