21945219137 has 2 divisors, whose sum is σ = 21945219138. Its totient is φ = 21945219136.

The previous prime is 21945219133. The next prime is 21945219161. The reversal of 21945219137 is 73191254912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20348737201 + 1596481936 = 142649^2 + 39956^2 .

It is a cyclic number.

It is not a de Polignac number, because 21945219137 - 2² = 21945219133 is a prime.

It is not a weakly prime, because it can be changed into another prime (21945219133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972609568 + 10972609569.

It is an arithmetic number, because the mean of its divisors is an integer number (10972609569).

Almost surely, 2^21945219137 is an apocalyptic number.

It is an amenable number.

21945219137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945219137 is an equidigital number, since it uses as much as digits as its factorization.

21945219137 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 44.

The spelling of 21945219137 in words is "twenty-one billion, nine hundred forty-five million, two hundred nineteen thousand, one hundred thirty-seven".