21201109961 has 2 divisors, whose sum is σ = 21201109962. Its totient is φ = 21201109960.

The previous prime is 21201109913. The next prime is 21201110027. The reversal of 21201109961 is 16990110212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14778049225 + 6423060736 = 121565^2 + 80144^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201109961 - 2¹⁰ = 21201108937 is a prime.

It is not a weakly prime, because it can be changed into another prime (21201109861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600554980 + 10600554981.

It is an arithmetic number, because the mean of its divisors is an integer number (10600554981).

Almost surely, 2^21201109961 is an apocalyptic number.

It is an amenable number.

21201109961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201109961 is an equidigital number, since it uses as much as digits as its factorization.

21201109961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 32.

The spelling of 21201109961 in words is "twenty-one billion, two hundred one million, one hundred nine thousand, nine hundred sixty-one".