20727989 has 2 divisors, whose sum is σ = 20727990. Its totient is φ = 20727988.

The previous prime is 20727979. The next prime is 20728009. The reversal of 20727989 is 98972702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20295025 + 432964 = 4505^2 + 658^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20727989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20727979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10363994 + 10363995.

It is an arithmetic number, because the mean of its divisors is an integer number (10363995).

Almost surely, 2^20727989 is an apocalyptic number.

It is an amenable number.

20727989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20727989 is an equidigital number, since it uses as much as digits as its factorization.

20727989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 20727989 is about 4552.8001273941. The cubic root of 20727989 is about 274.6960343896.

The spelling of 20727989 in words is "twenty million, seven hundred twenty-seven thousand, nine hundred eighty-nine".