21146229809 has 2 divisors, whose sum is σ = 21146229810. Its totient is φ = 21146229808.

The previous prime is 21146229791. The next prime is 21146229827. The reversal of 21146229809 is 90892264112.

It is a balanced prime because it is at equal distance from previous prime (21146229791) and next prime (21146229827).

It can be written as a sum of positive squares in only one way, i.e., 18686069809 + 2460160000 = 136697^2 + 49600^2 .

It is a cyclic number.

It is not a de Polignac number, because 21146229809 - 2⁸ = 21146229553 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21146229809.

It is not a weakly prime, because it can be changed into another prime (21146229829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573114904 + 10573114905.

It is an arithmetic number, because the mean of its divisors is an integer number (10573114905).

Almost surely, 2^21146229809 is an apocalyptic number.

It is an amenable number.

21146229809 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146229809 is an equidigital number, since it uses as much as digits as its factorization.

21146229809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 124416, while the sum is 44.

The spelling of 21146229809 in words is "twenty-one billion, one hundred forty-six million, two hundred twenty-nine thousand, eight hundred nine".