81766278 has 48 divisors (see below), whose sum is σ = 195947856. Its totient is φ = 24433920.

The previous prime is 81766273. The next prime is 81766301. The reversal of 81766278 is 87266718.

81766278 is a `hidden beast` number, since 8 + 17 + 6 + 627 + 8 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81766273) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11626 + ... + 17282.

It is an arithmetic number, because the mean of its divisors is an integer number (4082247).

Almost surely, 2^81766278 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81766278, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97973928).

81766278 is an abundant number, since it is smaller than the sum of its proper divisors (114181578).

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

81766278 is a wasteful number, since it uses less digits than its factorization.

81766278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5749 (or 5746 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 81766278 is about 9042.4707906634. The cubic root of 81766278 is about 434.0349911972.

The spelling of 81766278 in words is "eighty-one million, seven hundred sixty-six thousand, two hundred seventy-eight".