21707393909 has 2 divisors, whose sum is σ = 21707393910. Its totient is φ = 21707393908.

The previous prime is 21707393899. The next prime is 21707393971. The reversal of 21707393909 is 90939370712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20656013284 + 1051380625 = 143722^2 + 32425^2 .

It is a cyclic number.

It is not a de Polignac number, because 21707393909 - 2¹² = 21707389813 is a prime.

It is a super-3 number, since 3×21707393909³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21707393989) 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, 10853696954 + 10853696955.

It is an arithmetic number, because the mean of its divisors is an integer number (10853696955).

Almost surely, 2^21707393909 is an apocalyptic number.

It is an amenable number.

21707393909 is a deficient number, since it is larger than the sum of its proper divisors (1).

21707393909 is an equidigital number, since it uses as much as digits as its factorization.

21707393909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 642978, while the sum is 50.

The spelling of 21707393909 in words is "twenty-one billion, seven hundred seven million, three hundred ninety-three thousand, nine hundred nine".