20728637 has 2 divisors, whose sum is σ = 20728638. Its totient is φ = 20728636.

The previous prime is 20728633. The next prime is 20728691. The reversal of 20728637 is 73682702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19061956 + 1666681 = 4366^2 + 1291^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728637 - 2² = 20728633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20728597 and 20728606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20728633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10364318 + 10364319.

It is an arithmetic number, because the mean of its divisors is an integer number (10364319).

Almost surely, 2^20728637 is an apocalyptic number.

It is an amenable number.

20728637 is a deficient number, since it is larger than the sum of its proper divisors (1).

20728637 is an equidigital number, since it uses as much as digits as its factorization.

20728637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28224, while the sum is 35.

The square root of 20728637 is about 4552.8712918333. The cubic root of 20728637 is about 274.6988968827.

The spelling of 20728637 in words is "twenty million, seven hundred twenty-eight thousand, six hundred thirty-seven".