21111101021947 has 2 divisors, whose sum is σ = 21111101021948. Its totient is φ = 21111101021946.

The previous prime is 21111101021911. The next prime is 21111101021951. The reversal of 21111101021947 is 74912010111112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111101021947 is a prime.

It is not a weakly prime, because it can be changed into another prime (21111101024947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555550510973 + 10555550510974.

It is an arithmetic number, because the mean of its divisors is an integer number (10555550510974).

Almost surely, 2^{21111101021947} is an apocalyptic number.

21111101021947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111101021947 is an equidigital number, since it uses as much as digits as its factorization.

21111101021947 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 31.

The spelling of 21111101021947 in words is "twenty-one trillion, one hundred eleven billion, one hundred one million, twenty-one thousand, nine hundred forty-seven".