81777726 has 12 divisors (see below), whose sum is σ = 177185112. Its totient is φ = 27259236.

The previous prime is 81777677. The next prime is 81777727. The reversal of 81777726 is 62777718.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81777727) 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 5 ways as a sum of consecutive naturals, for example, 2271586 + ... + 2271621.

It is an arithmetic number, because the mean of its divisors is an integer number (14765426).

Almost surely, 2^81777726 is an apocalyptic number.

81777726 is an abundant number, since it is smaller than the sum of its proper divisors (95407386).

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

81777726 is a wasteful number, since it uses less digits than its factorization.

81777726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4543215 (or 4543212 counting only the distinct ones).

The product of its digits is 230496, while the sum is 45.

The square root of 81777726 is about 9043.1037813353. The cubic root of 81777726 is about 434.0552464940.

The spelling of 81777726 in words is "eighty-one million, seven hundred seventy-seven thousand, seven hundred twenty-six".