20668157 has 2 divisors, whose sum is σ = 20668158. Its totient is φ = 20668156.

The previous prime is 20668147. The next prime is 20668169. The reversal of 20668157 is 75186602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17023876 + 3644281 = 4126^2 + 1909^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20668157 is a prime.

It is a super-3 number, since 3×20668157³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20668117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10334078 + 10334079.

It is an arithmetic number, because the mean of its divisors is an integer number (10334079).

Almost surely, 2^20668157 is an apocalyptic number.

It is an amenable number.

20668157 is a deficient number, since it is larger than the sum of its proper divisors (1).

20668157 is an equidigital number, since it uses as much as digits as its factorization.

20668157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20668157 is about 4546.2244775198. The cubic root of 20668157 is about 274.4314733893.

The spelling of 20668157 in words is "twenty million, six hundred sixty-eight thousand, one hundred fifty-seven".