21806981351 has 2 divisors, whose sum is σ = 21806981352. Its totient is φ = 21806981350.

The previous prime is 21806981347. The next prime is 21806981411. The reversal of 21806981351 is 15318960812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21806981351 - 2² = 21806981347 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21806981851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10903490675 + 10903490676.

It is an arithmetic number, because the mean of its divisors is an integer number (10903490676).

Almost surely, 2^21806981351 is an apocalyptic number.

21806981351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21806981351 is an equidigital number, since it uses as much as digits as its factorization.

21806981351 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 103680, while the sum is 44.

The spelling of 21806981351 in words is "twenty-one billion, eight hundred six million, nine hundred eighty-one thousand, three hundred fifty-one".