21945219161 has 2 divisors, whose sum is σ = 21945219162. Its totient is φ = 21945219160.

The previous prime is 21945219137. The next prime is 21945219211. The reversal of 21945219161 is 16191254912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14318515600 + 7626703561 = 119660^2 + 87331^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21945219161 is a prime.

It is not a weakly prime, because it can be changed into another prime (21945219661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972609580 + 10972609581.

It is an arithmetic number, because the mean of its divisors is an integer number (10972609581).

Almost surely, 2^21945219161 is an apocalyptic number.

It is an amenable number.

21945219161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945219161 is an equidigital number, since it uses as much as digits as its factorization.

21945219161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 41.

The spelling of 21945219161 in words is "twenty-one billion, nine hundred forty-five million, two hundred nineteen thousand, one hundred sixty-one".