81661466 has 8 divisors (see below), whose sum is σ = 125098560. Its totient is φ = 39961948.

The previous prime is 81661457. The next prime is 81661469. The reversal of 81661466 is 66416618.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81661469) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 434276 + ... + 434463.

It is an arithmetic number, because the mean of its divisors is an integer number (15637320).

Almost surely, 2^81661466 is an apocalyptic number.

81661466 is a deficient number, since it is larger than the sum of its proper divisors (43437094).

81661466 is a wasteful number, since it uses less digits than its factorization.

81661466 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868788.

The product of its digits is 41472, while the sum is 38.

The square root of 81661466 is about 9036.6733923496. The cubic root of 81661466 is about 433.8494561639.

The spelling of 81661466 in words is "eighty-one million, six hundred sixty-one thousand, four hundred sixty-six".