21100099961 has 2 divisors, whose sum is σ = 21100099962. Its totient is φ = 21100099960.

The previous prime is 21100099907. The next prime is 21100100011. The reversal of 21100099961 is 16999000112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17810503936 + 3289596025 = 133456^2 + 57355^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100099961 - 2³⁴ = 3920230777 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100099901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550049980 + 10550049981.

It is an arithmetic number, because the mean of its divisors is an integer number (10550049981).

Almost surely, 2^21100099961 is an apocalyptic number.

It is an amenable number.

21100099961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100099961 is an equidigital number, since it uses as much as digits as its factorization.

21100099961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 38.

The spelling of 21100099961 in words is "twenty-one billion, one hundred million, ninety-nine thousand, nine hundred sixty-one".