81851783 has 8 divisors (see below), whose sum is σ = 88225200. Its totient is φ = 75489408.

The previous prime is 81851743. The next prime is 81851789. The reversal of 81851783 is 38715818.

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

It is a cyclic number.

It is not a de Polignac number, because 81851783 - 2¹⁶ = 81786247 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81851783.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81851789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19103 + ... + 22991.

It is an arithmetic number, because the mean of its divisors is an integer number (11028150).

Almost surely, 2^81851783 is an apocalyptic number.

81851783 is a deficient number, since it is larger than the sum of its proper divisors (6373417).

81851783 is a wasteful number, since it uses less digits than its factorization.

81851783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5521.

The product of its digits is 53760, while the sum is 41.

The square root of 81851783 is about 9047.1975218849. The cubic root of 81851783 is about 434.1862321650.

The spelling of 81851783 in words is "eighty-one million, eight hundred fifty-one thousand, seven hundred eighty-three".