81553855 has 8 divisors (see below), whose sum is σ = 98815392. Its totient is φ = 64609248.

The previous prime is 81553847. The next prime is 81553859. The reversal of 81553855 is 55835518.

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 81553855 - 2³ = 81553847 is a prime.

It is a super-2 number, since 2×81553855² = 13302062530722050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81553859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78664 + ... + 79693.

It is an arithmetic number, because the mean of its divisors is an integer number (12351924).

Almost surely, 2^81553855 is an apocalyptic number.

81553855 is a deficient number, since it is larger than the sum of its proper divisors (17261537).

81553855 is a wasteful number, since it uses less digits than its factorization.

81553855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158465.

The product of its digits is 120000, while the sum is 40.

The square root of 81553855 is about 9030.7173026288. The cubic root of 81553855 is about 433.6588011801.

The spelling of 81553855 in words is "eighty-one million, five hundred fifty-three thousand, eight hundred fifty-five".