81429409 has 2 divisors, whose sum is σ = 81429410. Its totient is φ = 81429408.

The previous prime is 81429379. The next prime is 81429437. The reversal of 81429409 is 90492418.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61152400 + 20277009 = 7820^2 + 4503^2 .

It is a cyclic number.

It is not a de Polignac number, because 81429409 - 2¹¹ = 81427361 is a prime.

It is not a weakly prime, because it can be changed into another prime (81429109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40714704 + 40714705.

It is an arithmetic number, because the mean of its divisors is an integer number (40714705).

Almost surely, 2^81429409 is an apocalyptic number.

It is an amenable number.

81429409 is a deficient number, since it is larger than the sum of its proper divisors (1).

81429409 is an equidigital number, since it uses as much as digits as its factorization.

81429409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 81429409 is about 9023.8245217868. The cubic root of 81429409 is about 433.4381102981.

The spelling of 81429409 in words is "eighty-one million, four hundred twenty-nine thousand, four hundred nine".