21121021009993 has 2 divisors, whose sum is σ = 21121021009994. Its totient is φ = 21121021009992.

The previous prime is 21121021009967. The next prime is 21121021010027. The reversal of 21121021009993 is 39990012012112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18237708336969 + 2883312673024 = 4270563^2 + 1698032^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121021009993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21121021009393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560510504996 + 10560510504997.

It is an arithmetic number, because the mean of its divisors is an integer number (10560510504997).

Almost surely, 2^{21121021009993} is an apocalyptic number.

It is an amenable number.

21121021009993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121021009993 is an equidigital number, since it uses as much as digits as its factorization.

21121021009993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17496, while the sum is 40.

The spelling of 21121021009993 in words is "twenty-one trillion, one hundred twenty-one billion, twenty-one million, nine thousand, nine hundred ninety-three".