21100220971 has 2 divisors, whose sum is σ = 21100220972. Its totient is φ = 21100220970.

The previous prime is 21100220963. The next prime is 21100221011. The reversal of 21100220971 is 17902200112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21100220971 - 2³ = 21100220963 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100220371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550110485 + 10550110486.

It is an arithmetic number, because the mean of its divisors is an integer number (10550110486).

Almost surely, 2^21100220971 is an apocalyptic number.

21100220971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100220971 is an equidigital number, since it uses as much as digits as its factorization.

21100220971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 25.

The spelling of 21100220971 in words is "twenty-one billion, one hundred million, two hundred twenty thousand, nine hundred seventy-one".