81220776 has 64 divisors (see below), whose sum is σ = 249916800. Its totient is φ = 21420288.

The previous prime is 81220759. The next prime is 81220787. The reversal of 81220776 is 67702218.

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 15 ways as a sum of consecutive naturals, for example, 16411 + ... + 20778.

It is an arithmetic number, because the mean of its divisors is an integer number (3904950).

Almost surely, 2^81220776 is an apocalyptic number.

It is an amenable number.

81220776 is an abundant number, since it is smaller than the sum of its proper divisors (168696024).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81220776 is a wasteful number, since it uses less digits than its factorization.

81220776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37218 (or 37214 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 81220776 is about 9012.2569870150. The cubic root of 81220776 is about 433.0676182965.

The spelling of 81220776 in words is "eighty-one million, two hundred twenty thousand, seven hundred seventy-six".