21212001848857 has 2 divisors, whose sum is σ = 21212001848858. Its totient is φ = 21212001848856.

The previous prime is 21212001848839. The next prime is 21212001848911. The reversal of 21212001848857 is 75884810021212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17343026934016 + 3868974914841 = 4164496^2 + 1966971^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212001848857 - 2³¹ = 21209854365209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212001848857.

It is not a weakly prime, because it can be changed into another prime (21212001848057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606000924428 + 10606000924429.

It is an arithmetic number, because the mean of its divisors is an integer number (10606000924429).

Almost surely, 2^{21212001848857} is an apocalyptic number.

It is an amenable number.

21212001848857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212001848857 is an equidigital number, since it uses as much as digits as its factorization.

21212001848857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 573440, while the sum is 49.

The spelling of 21212001848857 in words is "twenty-one trillion, two hundred twelve billion, one million, eight hundred forty-eight thousand, eight hundred fifty-seven".