21820082381 has 2 divisors, whose sum is σ = 21820082382. Its totient is φ = 21820082380.

The previous prime is 21820082377. The next prime is 21820082387. The reversal of 21820082381 is 18328002812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17106024100 + 4714058281 = 130790^2 + 68659^2 .

It is a cyclic number.

It is not a de Polignac number, because 21820082381 - 2² = 21820082377 is a prime.

It is a super-2 number, since 2×21820082381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21820082387) 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, 10910041190 + 10910041191.

It is an arithmetic number, because the mean of its divisors is an integer number (10910041191).

Almost surely, 2^21820082381 is an apocalyptic number.

It is an amenable number.

21820082381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21820082381 is an equidigital number, since it uses as much as digits as its factorization.

21820082381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12288, while the sum is 35.

The spelling of 21820082381 in words is "twenty-one billion, eight hundred twenty million, eighty-two thousand, three hundred eighty-one".