221021111001997 has 2 divisors, whose sum is σ = 221021111001998. Its totient is φ = 221021111001996.

The previous prime is 221021111001961. The next prime is 221021111002099. The reversal of 221021111001997 is 799100111120122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 150667499059561 + 70353611942436 = 12274669^2 + 8387706^2 .

It is a cyclic number.

It is not a de Polignac number, because 221021111001997 - 2¹⁵ = 221021110969229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221021111001697) 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, 110510555500998 + 110510555500999.

It is an arithmetic number, because the mean of its divisors is an integer number (110510555500999).

Almost surely, 2^{221021111001997} is an apocalyptic number.

It is an amenable number.

221021111001997 is a deficient number, since it is larger than the sum of its proper divisors (1).

221021111001997 is an equidigital number, since it uses as much as digits as its factorization.

221021111001997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4536, while the sum is 37.

The spelling of 221021111001997 in words is "two hundred twenty-one trillion, twenty-one billion, one hundred eleven million, one thousand, nine hundred ninety-seven".