21021031330181 has 2 divisors, whose sum is σ = 21021031330182. Its totient is φ = 21021031330180.

The previous prime is 21021031330147. The next prime is 21021031330219. The reversal of 21021031330181 is 18103313012012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18246694708225 + 2774336621956 = 4271615^2 + 1665634^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021031330181 is a prime.

It is a super-2 number, since 2×21021031330181² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21021031330181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021031339181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510515665090 + 10510515665091.

It is an arithmetic number, because the mean of its divisors is an integer number (10510515665091).

Almost surely, 2^{21021031330181} is an apocalyptic number.

It is an amenable number.

21021031330181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021031330181 is an equidigital number, since it uses as much as digits as its factorization.

21021031330181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 26.

Adding to 21021031330181 its reverse (18103313012012), we get a palindrome (39124344342193).

The spelling of 21021031330181 in words is "twenty-one trillion, twenty-one billion, thirty-one million, three hundred thirty thousand, one hundred eighty-one".