21011221199993 has 2 divisors, whose sum is σ = 21011221199994. Its totient is φ = 21011221199992.

The previous prime is 21011221199989. The next prime is 21011221199999. The reversal of 21011221199993 is 39999112211012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17533581785344 + 3477639414649 = 4187312^2 + 1864843^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011221199993 - 2² = 21011221199989 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011221199999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505610599996 + 10505610599997.

It is an arithmetic number, because the mean of its divisors is an integer number (10505610599997).

Almost surely, 2^{21011221199993} is an apocalyptic number.

It is an amenable number.

21011221199993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011221199993 is an equidigital number, since it uses as much as digits as its factorization.

21011221199993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 157464, while the sum is 50.

The spelling of 21011221199993 in words is "twenty-one trillion, eleven billion, two hundred twenty-one million, one hundred ninety-nine thousand, nine hundred ninety-three".