20011209999961 has 2 divisors, whose sum is σ = 20011209999962. Its totient is φ = 20011209999960.

The previous prime is 20011209999929. The next prime is 20011210000039. The reversal of 20011209999961 is 16999990211002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11238210294336 + 8772999705625 = 3352344^2 + 2961925^2 .

It is a cyclic number.

It is not a de Polignac number, because 20011209999961 - 2⁵ = 20011209999929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20011209999896 and 20011209999905.

It is not a weakly prime, because it can be changed into another prime (20011209999901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10005604999980 + 10005604999981.

It is an arithmetic number, because the mean of its divisors is an integer number (10005604999981).

Almost surely, 2^{20011209999961} is an apocalyptic number.

It is an amenable number.

20011209999961 is a deficient number, since it is larger than the sum of its proper divisors (1).

20011209999961 is an equidigital number, since it uses as much as digits as its factorization.

20011209999961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1417176, while the sum is 58.

The spelling of 20011209999961 in words is "twenty trillion, eleven billion, two hundred nine million, nine hundred ninety-nine thousand, nine hundred sixty-one".