81423241 has 2 divisors, whose sum is σ = 81423242. Its totient is φ = 81423240.

The previous prime is 81423239. The next prime is 81423247. The reversal of 81423241 is 14232418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67584841 + 13838400 = 8221^2 + 3720^2 .

It is a cyclic number.

It is not a de Polignac number, because 81423241 - 2¹ = 81423239 is a prime.

Together with 81423239, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81423247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40711620 + 40711621.

It is an arithmetic number, because the mean of its divisors is an integer number (40711621).

Almost surely, 2^81423241 is an apocalyptic number.

It is an amenable number.

81423241 is a deficient number, since it is larger than the sum of its proper divisors (1).

81423241 is an equidigital number, since it uses as much as digits as its factorization.

81423241 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 25.

The square root of 81423241 is about 9023.4827533497. The cubic root of 81423241 is about 433.4271662022.

Adding to 81423241 its reverse (14232418), we get a palindrome (95655659).

It can be divided in two parts, 8 and 1423241, that added together give a square (1423249 = 1193²).

The spelling of 81423241 in words is "eighty-one million, four hundred twenty-three thousand, two hundred forty-one".