81820655 has 16 divisors (see below), whose sum is σ = 114600960. Its totient is φ = 54910752.

The previous prime is 81820649. The next prime is 81820667. The reversal of 81820655 is 55602818.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81820655 - 2⁸ = 81820399 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a plaindrome in base 12.

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 15 ways as a sum of consecutive naturals, for example, 23225 + ... + 26514.

It is an arithmetic number, because the mean of its divisors is an integer number (7162560).

Almost surely, 2^81820655 is an apocalyptic number.

81820655 is a deficient number, since it is larger than the sum of its proper divisors (32780305).

81820655 is a wasteful number, since it uses less digits than its factorization.

81820655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49798.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 81820655 is about 9045.4770465686. The cubic root of 81820655 is about 434.1311852571.

The spelling of 81820655 in words is "eighty-one million, eight hundred twenty thousand, six hundred fifty-five".