2102009981 has 2 divisors, whose sum is σ = 2102009982. Its totient is φ = 2102009980.

The previous prime is 2102009969. The next prime is 2102009983. The reversal of 2102009981 is 1899002012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1786414756 + 315595225 = 42266^2 + 17765^2 .

It is a cyclic number.

It is not a de Polignac number, because 2102009981 - 2²⁶ = 2034901117 is a prime.

It is a super-2 number, since 2×2102009981² = 8836891920447240722, which contains 22 as substring.

Together with 2102009983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2102009983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1051004990 + 1051004991.

It is an arithmetic number, because the mean of its divisors is an integer number (1051004991).

Almost surely, 2^2102009981 is an apocalyptic number.

It is an amenable number.

2102009981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2102009981 is an equidigital number, since it uses as much as digits as its factorization.

2102009981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 2102009981 is about 45847.6823950786. The cubic root of 2102009981 is about 1280.9875965788.

The spelling of 2102009981 in words is "two billion, one hundred two million, nine thousand, nine hundred eighty-one".