21425633909 has 2 divisors, whose sum is σ = 21425633910. Its totient is φ = 21425633908.

The previous prime is 21425633881. The next prime is 21425633921. The reversal of 21425633909 is 90933652412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18992974225 + 2432659684 = 137815^2 + 49322^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21425633909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21425633909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21425633959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712816954 + 10712816955.

It is an arithmetic number, because the mean of its divisors is an integer number (10712816955).

Almost surely, 2^21425633909 is an apocalyptic number.

It is an amenable number.

21425633909 is a deficient number, since it is larger than the sum of its proper divisors (1).

21425633909 is an equidigital number, since it uses as much as digits as its factorization.

21425633909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 349920, while the sum is 44.

The spelling of 21425633909 in words is "twenty-one billion, four hundred twenty-five million, six hundred thirty-three thousand, nine hundred nine".