81210855 has 32 divisors (see below), whose sum is σ = 146331648. Its totient is φ = 38102400.

The previous prime is 81210823. The next prime is 81210881. The reversal of 81210855 is 55801218.

It is not a de Polignac number, because 81210855 - 2⁵ = 81210823 is a prime.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 2824 + ... + 13053.

It is an arithmetic number, because the mean of its divisors is an integer number (4572864).

Almost surely, 2^81210855 is an apocalyptic number.

81210855 is a deficient number, since it is larger than the sum of its proper divisors (65120793).

81210855 is a wasteful number, since it uses less digits than its factorization.

81210855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15927.

The product of its (nonzero) digits is 3200, while the sum is 30.

The square root of 81210855 is about 9011.7065531452. The cubic root of 81210855 is about 433.0499847180.

The spelling of 81210855 in words is "eighty-one million, two hundred ten thousand, eight hundred fifty-five".