2121020981 has 2 divisors, whose sum is σ = 2121020982. Its totient is φ = 2121020980.

The previous prime is 2121020947. The next prime is 2121020983. The reversal of 2121020981 is 1890201212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1097596900 + 1023424081 = 33130^2 + 31991^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121020981 - 2³⁰ = 1047279157 is a prime.

It is a super-2 number, since 2×2121020981² = 8997460003684404722, which contains 22 as substring.

Together with 2121020983, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2121020981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2121020983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060510490 + 1060510491.

It is an arithmetic number, because the mean of its divisors is an integer number (1060510491).

Almost surely, 2^2121020981 is an apocalyptic number.

It is an amenable number.

2121020981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121020981 is an equidigital number, since it uses as much as digits as its factorization.

2121020981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 2121020981 is about 46054.5435434985. The cubic root of 2121020981 is about 1284.8378485961.

The spelling of 2121020981 in words is "two billion, one hundred twenty-one million, twenty thousand, nine hundred eighty-one".