21956378219 has 2 divisors, whose sum is σ = 21956378220. Its totient is φ = 21956378218.

The previous prime is 21956378209. The next prime is 21956378233. The reversal of 21956378219 is 91287365912.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21956378219 is a prime.

It is a super-2 number, since 2×21956378219² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21956378209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978189109 + 10978189110.

It is an arithmetic number, because the mean of its divisors is an integer number (10978189110).

Almost surely, 2^21956378219 is an apocalyptic number.

21956378219 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956378219 is an equidigital number, since it uses as much as digits as its factorization.

21956378219 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 53.

The spelling of 21956378219 in words is "twenty-one billion, nine hundred fifty-six million, three hundred seventy-eight thousand, two hundred nineteen".