20211211997 has 2 divisors, whose sum is σ = 20211211998. Its totient is φ = 20211211996.

The previous prime is 20211211961. The next prime is 20211212003. The reversal of 20211211997 is 79911211202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19647909241 + 563302756 = 140171^2 + 23734^2 .

It is a cyclic number.

It is not a de Polignac number, because 20211211997 - 2¹⁰ = 20211210973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20211211597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105605998 + 10105605999.

It is an arithmetic number, because the mean of its divisors is an integer number (10105605999).

Almost surely, 2^20211211997 is an apocalyptic number.

It is an amenable number.

20211211997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211211997 is an equidigital number, since it uses as much as digits as its factorization.

20211211997 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 35.

The spelling of 20211211997 in words is "twenty billion, two hundred eleven million, two hundred eleven thousand, nine hundred ninety-seven".