81851766 has 8 divisors (see below), whose sum is σ = 163703544. Its totient is φ = 27283920.

The previous prime is 81851743. The next prime is 81851789. The reversal of 81851766 is 66715818.

It is an interprime number because it is at equal distance from previous prime (81851743) and next prime (81851789).

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

81851766 is an admirable number.

It is a congruent number.

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, 6820975 + ... + 6820986.

It is an arithmetic number, because the mean of its divisors is an integer number (20462943).

Almost surely, 2^81851766 is an apocalyptic number.

81851766 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81851766 is a wasteful number, since it uses less digits than its factorization.

81851766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13641966.

The product of its digits is 80640, while the sum is 42.

The square root of 81851766 is about 9047.1965823674. The cubic root of 81851766 is about 434.1862021060.

The spelling of 81851766 in words is "eighty-one million, eight hundred fifty-one thousand, seven hundred sixty-six".