20963981 has 2 divisors, whose sum is σ = 20963982. Its totient is φ = 20963980.

The previous prime is 20963951. The next prime is 20963989. The reversal of 20963981 is 18936902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14668900 + 6295081 = 3830^2 + 2509^2 .

It is a cyclic number.

It is not a de Polignac number, because 20963981 - 2¹⁰ = 20962957 is a prime.

It is a super-2 number, since 2×20963981² = 878976998736722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20963989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10481990 + 10481991.

It is an arithmetic number, because the mean of its divisors is an integer number (10481991).

Almost surely, 2^20963981 is an apocalyptic number.

It is an amenable number.

20963981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20963981 is an equidigital number, since it uses as much as digits as its factorization.

20963981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20963981 is about 4578.6440132423. The cubic root of 20963981 is about 275.7345913539.

The spelling of 20963981 in words is "twenty million, nine hundred sixty-three thousand, nine hundred eighty-one".