20389657 has 2 divisors, whose sum is σ = 20389658. Its totient is φ = 20389656.

The previous prime is 20389643. The next prime is 20389667. The reversal of 20389657 is 75698302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17816841 + 2572816 = 4221^2 + 1604^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20389657 is a prime.

It is a super-2 number, since 2×20389657² = 831476225155298, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20389667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10194828 + 10194829.

It is an arithmetic number, because the mean of its divisors is an integer number (10194829).

Almost surely, 2^20389657 is an apocalyptic number.

It is an amenable number.

20389657 is a deficient number, since it is larger than the sum of its proper divisors (1).

20389657 is an equidigital number, since it uses as much as digits as its factorization.

20389657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90720, while the sum is 40.

The square root of 20389657 is about 4515.4907817423. The cubic root of 20389657 is about 273.1932554444.

The spelling of 20389657 in words is "twenty million, three hundred eighty-nine thousand, six hundred fifty-seven".