87431209 has 2 divisors, whose sum is σ = 87431210. Its totient is φ = 87431208.

The previous prime is 87431207. The next prime is 87431213. The reversal of 87431209 is 90213478.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83667609 + 3763600 = 9147^2 + 1940^2 .

It is a cyclic number.

It is not a de Polignac number, because 87431209 - 2¹ = 87431207 is a prime.

Together with 87431207, it forms a pair of twin primes.

It is equal to p_5076691 and since 87431209 and 5076691 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (87431203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43715604 + 43715605.

It is an arithmetic number, because the mean of its divisors is an integer number (43715605).

Almost surely, 2^87431209 is an apocalyptic number.

It is an amenable number.

87431209 is a deficient number, since it is larger than the sum of its proper divisors (1).

87431209 is an equidigital number, since it uses as much as digits as its factorization.

87431209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 87431209 is about 9350.4657103269. The cubic root of 87431209 is about 443.8356278850.

The spelling of 87431209 in words is "eighty-seven million, four hundred thirty-one thousand, two hundred nine".