21100802857 has 2 divisors, whose sum is σ = 21100802858. Its totient is φ = 21100802856.

The previous prime is 21100802791. The next prime is 21100802867. The reversal of 21100802857 is 75820800112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16530502041 + 4570300816 = 128571^2 + 67604^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100802857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100802867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550401428 + 10550401429.

It is an arithmetic number, because the mean of its divisors is an integer number (10550401429).

Almost surely, 2^21100802857 is an apocalyptic number.

It is an amenable number.

21100802857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100802857 is an equidigital number, since it uses as much as digits as its factorization.

21100802857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8960, while the sum is 34.

The spelling of 21100802857 in words is "twenty-one billion, one hundred million, eight hundred two thousand, eight hundred fifty-seven".