21658137409 has 2 divisors, whose sum is σ = 21658137410. Its totient is φ = 21658137408.

The previous prime is 21658137379. The next prime is 21658137439. The reversal of 21658137409 is 90473185612.

It is a balanced prime because it is at equal distance from previous prime (21658137379) and next prime (21658137439).

It can be written as a sum of positive squares in only one way, i.e., 12416199184 + 9241938225 = 111428^2 + 96135^2 .

It is a cyclic number.

It is not a de Polignac number, because 21658137409 - 2¹¹ = 21658135361 is a prime.

It is not a weakly prime, because it can be changed into another prime (21658137439) 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, 10829068704 + 10829068705.

It is an arithmetic number, because the mean of its divisors is an integer number (10829068705).

It is a 1-persistent number, because it is pandigital, but 2⋅21658137409 = 43316274818 is not.

Almost surely, 2^21658137409 is an apocalyptic number.

It is an amenable number.

21658137409 is a deficient number, since it is larger than the sum of its proper divisors (1).

21658137409 is an equidigital number, since it uses as much as digits as its factorization.

21658137409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 46.

The spelling of 21658137409 in words is "twenty-one billion, six hundred fifty-eight million, one hundred thirty-seven thousand, four hundred nine".