21171224605381 has 2 divisors, whose sum is σ = 21171224605382. Its totient is φ = 21171224605380.

The previous prime is 21171224605373. The next prime is 21171224605393. The reversal of 21171224605381 is 18350642217112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20893437632356 + 277786973025 = 4570934^2 + 527055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21171224605381 - 2³ = 21171224605373 is a prime.

It is a super-2 number, since 2×21171224605381² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21171224605361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585612302690 + 10585612302691.

It is an arithmetic number, because the mean of its divisors is an integer number (10585612302691).

Almost surely, 2^{21171224605381} is an apocalyptic number.

It is an amenable number.

21171224605381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21171224605381 is an equidigital number, since it uses as much as digits as its factorization.

21171224605381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 161280, while the sum is 43.

The spelling of 21171224605381 in words is "twenty-one trillion, one hundred seventy-one billion, two hundred twenty-four million, six hundred five thousand, three hundred eighty-one".