81823939 has 2 divisors, whose sum is σ = 81823940. Its totient is φ = 81823938.

The previous prime is 81823927. The next prime is 81823967. The reversal of 81823939 is 93932818.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81823939 - 2¹⁷ = 81692867 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81823895 and 81823904.

It is not a weakly prime, because it can be changed into another prime (81823979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40911969 + 40911970.

It is an arithmetic number, because the mean of its divisors is an integer number (40911970).

Almost surely, 2^81823939 is an apocalyptic number.

81823939 is a deficient number, since it is larger than the sum of its proper divisors (1).

81823939 is an equidigital number, since it uses as much as digits as its factorization.

81823939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 43.

The square root of 81823939 is about 9045.6585719338. The cubic root of 81823939 is about 434.1369933575.

It can be divided in two parts, 8182 and 3939, that added together give a palindrome (12121).

The spelling of 81823939 in words is "eighty-one million, eight hundred twenty-three thousand, nine hundred thirty-nine".