71988409 has 2 divisors, whose sum is σ = 71988410. Its totient is φ = 71988408.

The previous prime is 71988401. The next prime is 71988467. The reversal of 71988409 is 90488917.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66912400 + 5076009 = 8180^2 + 2253^2 .

It is a cyclic number.

It is not a de Polignac number, because 71988409 - 2³ = 71988401 is a prime.

It is not a weakly prime, because it can be changed into another prime (71988401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35994204 + 35994205.

It is an arithmetic number, because the mean of its divisors is an integer number (35994205).

Almost surely, 2^71988409 is an apocalyptic number.

It is an amenable number.

71988409 is a deficient number, since it is larger than the sum of its proper divisors (1).

71988409 is an equidigital number, since it uses as much as digits as its factorization.

71988409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 71988409 is about 8484.5983405227. The cubic root of 71988409 is about 415.9944391053.

The spelling of 71988409 in words is "seventy-one million, nine hundred eighty-eight thousand, four hundred nine".