2101208981 has 2 divisors, whose sum is σ = 2101208982. Its totient is φ = 2101208980.

The previous prime is 2101208927. The next prime is 2101209017. The reversal of 2101208981 is 1898021012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2094526756 + 6682225 = 45766^2 + 2585^2 .

It is a cyclic number.

It is not a de Polignac number, because 2101208981 - 2²² = 2097014677 is a prime.

It is a super-2 number, since 2×2101208981² = 8830158363670116722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2101208581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050604490 + 1050604491.

It is an arithmetic number, because the mean of its divisors is an integer number (1050604491).

Almost surely, 2^2101208981 is an apocalyptic number.

It is an amenable number.

2101208981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2101208981 is an equidigital number, since it uses as much as digits as its factorization.

2101208981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 32.

The square root of 2101208981 is about 45838.9461157213. The cubic root of 2101208981 is about 1280.8248632213.

Adding to 2101208981 its reverse (1898021012), we get a palindrome (3999229993).

The spelling of 2101208981 in words is "two billion, one hundred one million, two hundred eight thousand, nine hundred eighty-one".