21948426917 has 2 divisors, whose sum is σ = 21948426918. Its totient is φ = 21948426916.

The previous prime is 21948426779. The next prime is 21948426923. The reversal of 21948426917 is 71962484912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15718639876 + 6229787041 = 125374^2 + 78929^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21948426917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21948426937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10974213458 + 10974213459.

It is an arithmetic number, because the mean of its divisors is an integer number (10974213459).

Almost surely, 2^21948426917 is an apocalyptic number.

It is an amenable number.

21948426917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21948426917 is an equidigital number, since it uses as much as digits as its factorization.

21948426917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1741824, while the sum is 53.

The spelling of 21948426917 in words is "twenty-one billion, nine hundred forty-eight million, four hundred twenty-six thousand, nine hundred seventeen".