81778323 has 32 divisors (see below), whose sum is σ = 122330880. Its totient is φ = 48176640.

The previous prime is 81778321. The next prime is 81778327. The reversal of 81778323 is 32387718.

It is not a de Polignac number, because 81778323 - 2¹ = 81778321 is a prime.

It is a super-2 number, since 2×81778323² = 13375388225384658, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81778321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 199743 + ... + 200151.

It is an arithmetic number, because the mean of its divisors is an integer number (3822840).

Almost surely, 2^81778323 is an apocalyptic number.

81778323 is a gapful number since it is divisible by the number (83) formed by its first and last digit.

81778323 is a deficient number, since it is larger than the sum of its proper divisors (40552557).

81778323 is a wasteful number, since it uses less digits than its factorization.

81778323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 579.

The product of its digits is 56448, while the sum is 39.

The square root of 81778323 is about 9043.1367898534. The cubic root of 81778323 is about 434.0563027326.

The spelling of 81778323 in words is "eighty-one million, seven hundred seventy-eight thousand, three hundred twenty-three".