21220221019997 has 2 divisors, whose sum is σ = 21220221019998. Its totient is φ = 21220221019996.

The previous prime is 21220221019993. The next prime is 21220221020143. The reversal of 21220221019997 is 79991012202212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17086599356836 + 4133621663161 = 4133594^2 + 2033131^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220221019997 - 2² = 21220221019993 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220221019993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610110509998 + 10610110509999.

It is an arithmetic number, because the mean of its divisors is an integer number (10610110509999).

Almost surely, 2^{21220221019997} is an apocalyptic number.

It is an amenable number.

21220221019997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220221019997 is an equidigital number, since it uses as much as digits as its factorization.

21220221019997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 163296, while the sum is 47.

The spelling of 21220221019997 in words is "twenty-one trillion, two hundred twenty billion, two hundred twenty-one million, nineteen thousand, nine hundred ninety-seven".