81269999 has 2 divisors, whose sum is σ = 81270000. Its totient is φ = 81269998.

The previous prime is 81269989. The next prime is 81270001. The reversal of 81269999 is 99996218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81269999 - 2⁴ = 81269983 is a prime.

Together with 81270001, it forms a pair of twin primes.

It is a Chen prime.

81269999 is a modest number, since divided by 9999 gives 8126 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 81269999.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81269989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40634999 + 40635000.

It is an arithmetic number, because the mean of its divisors is an integer number (40635000).

Almost surely, 2^81269999 is an apocalyptic number.

81269999 is a deficient number, since it is larger than the sum of its proper divisors (1).

81269999 is an equidigital number, since it uses as much as digits as its factorization.

81269999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 629856, while the sum is 53.

The square root of 81269999 is about 9014.9874653268. The cubic root of 81269999 is about 433.1550859929.

The spelling of 81269999 in words is "eighty-one million, two hundred sixty-nine thousand, nine hundred ninety-nine".