21612105062381 has 2 divisors, whose sum is σ = 21612105062382. Its totient is φ = 21612105062380.

The previous prime is 21612105062329. The next prime is 21612105062393. The reversal of 21612105062381 is 18326050121612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12651601634281 + 8960503428100 = 3556909^2 + 2993410^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21612105062381 is a prime.

It is a super-2 number, since 2×21612105062381² (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 (21612105062281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806052531190 + 10806052531191.

It is an arithmetic number, because the mean of its divisors is an integer number (10806052531191).

Almost surely, 2^{21612105062381} is an apocalyptic number.

It is an amenable number.

21612105062381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21612105062381 is an equidigital number, since it uses as much as digits as its factorization.

21612105062381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34560, while the sum is 38.

Adding to 21612105062381 its reverse (18326050121612), we get a palindrome (39938155183993).

The spelling of 21612105062381 in words is "twenty-one trillion, six hundred twelve billion, one hundred five million, sixty-two thousand, three hundred eighty-one".