21323509901 has 2 divisors, whose sum is σ = 21323509902. Its totient is φ = 21323509900.

The previous prime is 21323509891. The next prime is 21323509919. The reversal of 21323509901 is 10990532312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18487840900 + 2835669001 = 135970^2 + 53251^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21323509901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21323509201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661754950 + 10661754951.

It is an arithmetic number, because the mean of its divisors is an integer number (10661754951).

Almost surely, 2^21323509901 is an apocalyptic number.

It is an amenable number.

21323509901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323509901 is an equidigital number, since it uses as much as digits as its factorization.

21323509901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14580, while the sum is 35.

The spelling of 21323509901 in words is "twenty-one billion, three hundred twenty-three million, five hundred nine thousand, nine hundred one".