20706557 has 2 divisors, whose sum is σ = 20706558. Its totient is φ = 20706556.

The previous prime is 20706503. The next prime is 20706559. The reversal of 20706557 is 75560702.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11909401 + 8797156 = 3451^2 + 2966^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20706557 is a prime.

Together with 20706559, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20706559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10353278 + 10353279.

It is an arithmetic number, because the mean of its divisors is an integer number (10353279).

Almost surely, 2^20706557 is an apocalyptic number.

It is an amenable number.

20706557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20706557 is an equidigital number, since it uses as much as digits as its factorization.

20706557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14700, while the sum is 32.

The square root of 20706557 is about 4550.4458023363. The cubic root of 20706557 is about 274.6013264457.

The spelling of 20706557 in words is "twenty million, seven hundred six thousand, five hundred fifty-seven".