20933981 has 2 divisors, whose sum is σ = 20933982. Its totient is φ = 20933980.

The previous prime is 20933977. The next prime is 20933989. The reversal of 20933981 is 18933902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15602500 + 5331481 = 3950^2 + 2309^2 .

It is a cyclic number.

It is not a de Polignac number, because 20933981 - 2² = 20933977 is a prime.

It is a super-2 number, since 2×20933981² = 876463121016722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20933989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10466990 + 10466991.

It is an arithmetic number, because the mean of its divisors is an integer number (10466991).

Almost surely, 2^20933981 is an apocalyptic number.

It is an amenable number.

20933981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20933981 is an equidigital number, since it uses as much as digits as its factorization.

20933981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 20933981 is about 4575.3667612553. The cubic root of 20933981 is about 275.6030007825.

The spelling of 20933981 in words is "twenty million, nine hundred thirty-three thousand, nine hundred eighty-one".