21720350423 has 2 divisors, whose sum is σ = 21720350424. Its totient is φ = 21720350422.

The previous prime is 21720350411. The next prime is 21720350453. The reversal of 21720350423 is 32405302712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21720350423 - 2⁶ = 21720350359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21720350453) 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, 10860175211 + 10860175212.

It is an arithmetic number, because the mean of its divisors is an integer number (10860175212).

Almost surely, 2^21720350423 is an apocalyptic number.

21720350423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21720350423 is an equidigital number, since it uses as much as digits as its factorization.

21720350423 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 29.

The spelling of 21720350423 in words is "twenty-one billion, seven hundred twenty million, three hundred fifty thousand, four hundred twenty-three".