81841851 has 24 divisors (see below), whose sum is σ = 145498080. Its totient is φ = 43168896.

The previous prime is 81841831. The next prime is 81841871. The reversal of 81841851 is 15814818.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81841831) and next prime (81841871).

It is not a de Polignac number, because 81841851 - 2⁶ = 81841787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81841801) 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, 49146 + ... + 50783.

It is an arithmetic number, because the mean of its divisors is an integer number (6062420).

Almost surely, 2^81841851 is an apocalyptic number.

81841851 is a deficient number, since it is larger than the sum of its proper divisors (63656229).

81841851 is a wasteful number, since it uses less digits than its factorization.

81841851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99955 (or 99952 counting only the distinct ones).

The product of its digits is 10240, while the sum is 36.

The square root of 81841851 is about 9046.6486059756. The cubic root of 81841851 is about 434.1686698838.

The spelling of 81841851 in words is "eighty-one million, eight hundred forty-one thousand, eight hundred fifty-one".