21211211020997 has 2 divisors, whose sum is σ = 21211211020998. Its totient is φ = 21211211020996.

The previous prime is 21211211020963. The next prime is 21211211021083. The reversal of 21211211020997 is 79902011211212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18787292093761 + 2423918927236 = 4334431^2 + 1556894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211211020997 - 2¹⁶ = 21211210955461 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21211211020997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211211020907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605605510498 + 10605605510499.

It is an arithmetic number, because the mean of its divisors is an integer number (10605605510499).

Almost surely, 2^{21211211020997} is an apocalyptic number.

It is an amenable number.

21211211020997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211211020997 is an equidigital number, since it uses as much as digits as its factorization.

21211211020997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 38.

The spelling of 21211211020997 in words is "twenty-one trillion, two hundred eleven billion, two hundred eleven million, twenty thousand, nine hundred ninety-seven".