21112020121961 has 2 divisors, whose sum is σ = 21112020121962. Its totient is φ = 21112020121960.

The previous prime is 21112020121949. The next prime is 21112020122041. The reversal of 21112020121961 is 16912102021112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18562310560000 + 2549709561961 = 4308400^2 + 1596781^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112020121961 - 2⁴² = 16713973610857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21112020121931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556010060980 + 10556010060981.

It is an arithmetic number, because the mean of its divisors is an integer number (10556010060981).

Almost surely, 2^{21112020121961} is an apocalyptic number.

It is an amenable number.

21112020121961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112020121961 is an equidigital number, since it uses as much as digits as its factorization.

21112020121961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 29.

The spelling of 21112020121961 in words is "twenty-one trillion, one hundred twelve billion, twenty million, one hundred twenty-one thousand, nine hundred sixty-one".