21010001011997 has 2 divisors, whose sum is σ = 21010001011998. Its totient is φ = 21010001011996.

The previous prime is 21010001011991. The next prime is 21010001012083. The reversal of 21010001011997 is 79911010001012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11619876534436 + 9390124477561 = 3408794^2 + 3064331^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21010001011997 is a prime.

It is a super-2 number, since 2×21010001011997² (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 (21010001011991) 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, 10505000505998 + 10505000505999.

It is an arithmetic number, because the mean of its divisors is an integer number (10505000505999).

Almost surely, 2^{21010001011997} is an apocalyptic number.

It is an amenable number.

21010001011997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010001011997 is an equidigital number, since it uses as much as digits as its factorization.

21010001011997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134, while the sum is 32.

The spelling of 21010001011997 in words is "twenty-one trillion, ten billion, one million, eleven thousand, nine hundred ninety-seven".