81555555 has 8 divisors (see below), whose sum is σ = 130488912. Its totient is φ = 43496288.

The previous prime is 81555547. The next prime is 81555557. The reversal of 81555555 is 55555518.

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 81555555 - 2³ = 81555547 is a prime.

81555555 is a modest number, since divided by 55555 gives 815 as remainder.

It is not an unprimeable number, because it can be changed into a prime (81555557) by changing a digit.

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, 2718504 + ... + 2718533.

It is an arithmetic number, because the mean of its divisors is an integer number (16311114).

Almost surely, 2^81555555 is an apocalyptic number.

81555555 is a deficient number, since it is larger than the sum of its proper divisors (48933357).

81555555 is a wasteful number, since it uses less digits than its factorization.

81555555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5437045.

The product of its digits is 125000, while the sum is 39.

The square root of 81555555 is about 9030.8114253371. The cubic root of 81555555 is about 433.6618143826.

The spelling of 81555555 in words is "eighty-one million, five hundred fifty-five thousand, five hundred fifty-five".