21100100011961 has 2 divisors, whose sum is σ = 21100100011962. Its totient is φ = 21100100011960.

The previous prime is 21100100011957. The next prime is 21100100012003. The reversal of 21100100011961 is 16911000100112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15627513517225 + 5472586494736 = 3953165^2 + 2339356^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100100011961 - 2² = 21100100011957 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100100011061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550050005980 + 10550050005981.

It is an arithmetic number, because the mean of its divisors is an integer number (10550050005981).

Almost surely, 2^{21100100011961} is an apocalyptic number.

It is an amenable number.

21100100011961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100100011961 is an equidigital number, since it uses as much as digits as its factorization.

21100100011961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 23.

The spelling of 21100100011961 in words is "twenty-one trillion, one hundred billion, one hundred million, eleven thousand, nine hundred sixty-one".