999987409 has 2 divisors, whose sum is σ = 999987410. Its totient is φ = 999987408.

The previous prime is 999987389. The next prime is 999987421. The reversal of 999987409 is 904789999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 787644225 + 212343184 = 28065^2 + 14572^2 .

It is a cyclic number.

It is not a de Polignac number, because 999987409 - 2⁵ = 999987377 is a prime.

It is not a weakly prime, because it can be changed into another prime (999987449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499993704 + 499993705.

It is an arithmetic number, because the mean of its divisors is an integer number (499993705).

Almost surely, 2^999987409 is an apocalyptic number.

It is an amenable number.

999987409 is a deficient number, since it is larger than the sum of its proper divisors (1).

999987409 is an equidigital number, since it uses as much as digits as its factorization.

999987409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13226976, while the sum is 64.

The square root of 999987409 is about 31622.5775198670. The cubic root of 999987409 is about 999.9958029824.

The spelling of 999987409 in words is "nine hundred ninety-nine million, nine hundred eighty-seven thousand, four hundred nine".