21316732609 has 2 divisors, whose sum is σ = 21316732610. Its totient is φ = 21316732608.

The previous prime is 21316732589. The next prime is 21316732637. The reversal of 21316732609 is 90623761312.

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., 21170250000 + 146482609 = 145500^2 + 12103^2 .

It is a cyclic number.

It is not a de Polignac number, because 21316732609 - 2²¹ = 21314635457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21316732639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10658366304 + 10658366305.

It is an arithmetic number, because the mean of its divisors is an integer number (10658366305).

Almost surely, 2^21316732609 is an apocalyptic number.

It is an amenable number.

21316732609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21316732609 is an equidigital number, since it uses as much as digits as its factorization.

21316732609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 40.

The spelling of 21316732609 in words is "twenty-one billion, three hundred sixteen million, seven hundred thirty-two thousand, six hundred nine".