81855401 has 4 divisors (see below), whose sum is σ = 86163600. Its totient is φ = 77547204.

The previous prime is 81855377. The next prime is 81855419. The reversal of 81855401 is 10455818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 10455818 = 2 ⋅5227909.

It is a cyclic number.

It is not a de Polignac number, because 81855401 - 2⁶ = 81855337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81855491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2154071 + ... + 2154108.

It is an arithmetic number, because the mean of its divisors is an integer number (21540900).

Almost surely, 2^81855401 is an apocalyptic number.

It is an amenable number.

81855401 is a deficient number, since it is larger than the sum of its proper divisors (4308199).

81855401 is a wasteful number, since it uses less digits than its factorization.

81855401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4308198.

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

The square root of 81855401 is about 9047.3974710963. The cubic root of 81855401 is about 434.1926293486.

The spelling of 81855401 in words is "eighty-one million, eight hundred fifty-five thousand, four hundred one".