81666348 has 12 divisors (see below), whose sum is σ = 190554840. Its totient is φ = 27222112.

The previous prime is 81666323. The next prime is 81666379. The reversal of 81666348 is 84366618.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3402753 + ... + 3402776.

It is an arithmetic number, because the mean of its divisors is an integer number (15879570).

Almost surely, 2^81666348 is an apocalyptic number.

It is an amenable number.

81666348 is an abundant number, since it is smaller than the sum of its proper divisors (108888492).

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

81666348 is a wasteful number, since it uses less digits than its factorization.

81666348 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6805536 (or 6805534 counting only the distinct ones).

The product of its digits is 165888, while the sum is 42.

The square root of 81666348 is about 9036.9435098378. The cubic root of 81666348 is about 433.8581016566.

The spelling of 81666348 in words is "eighty-one million, six hundred sixty-six thousand, three hundred forty-eight".