81365555 has 8 divisors (see below), whose sum is σ = 97912800. Its totient is φ = 64909696.

The previous prime is 81365539. The next prime is 81365563. The reversal of 81365555 is 55556318.

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 81365555 - 2⁴ = 81365539 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20870 + ... + 24459.

It is an arithmetic number, because the mean of its divisors is an integer number (12239100).

Almost surely, 2^81365555 is an apocalyptic number.

81365555 is a deficient number, since it is larger than the sum of its proper divisors (16547245).

81365555 is a wasteful number, since it uses less digits than its factorization.

81365555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45693.

The product of its digits is 90000, while the sum is 38.

The square root of 81365555 is about 9020.2857493541. The cubic root of 81365555 is about 433.3247851700.

The spelling of 81365555 in words is "eighty-one million, three hundred sixty-five thousand, five hundred fifty-five".