20579981 has 2 divisors, whose sum is σ = 20579982. Its totient is φ = 20579980.

The previous prime is 20579971. The next prime is 20580017. The reversal of 20579981 is 18997502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11222500 + 9357481 = 3350^2 + 3059^2 .

It is a cyclic number.

It is not a de Polignac number, because 20579981 - 2¹⁴ = 20563597 is a prime.

It is a super-2 number, since 2×20579981² = 847071235920722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20579971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10289990 + 10289991.

It is an arithmetic number, because the mean of its divisors is an integer number (10289991).

Almost surely, 2^20579981 is an apocalyptic number.

It is an amenable number.

20579981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20579981 is an equidigital number, since it uses as much as digits as its factorization.

20579981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 20579981 is about 4536.5163947681. The cubic root of 20579981 is about 274.0406505479.

The spelling of 20579981 in words is "twenty million, five hundred seventy-nine thousand, nine hundred eighty-one".