21021223122791 has 2 divisors, whose sum is σ = 21021223122792. Its totient is φ = 21021223122790.

The previous prime is 21021223122773. The next prime is 21021223122827. The reversal of 21021223122791 is 19722132212012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021223122791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021223122701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510611561395 + 10510611561396.

It is an arithmetic number, because the mean of its divisors is an integer number (10510611561396).

Almost surely, 2^{21021223122791} is an apocalyptic number.

21021223122791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021223122791 is an equidigital number, since it uses as much as digits as its factorization.

21021223122791 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 35.

The spelling of 21021223122791 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-three million, one hundred twenty-two thousand, seven hundred ninety-one".