20570021 has 2 divisors, whose sum is σ = 20570022. Its totient is φ = 20570020.

The previous prime is 20569999. The next prime is 20570029. The reversal of 20570021 is 12007502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 220900 = 4511^2 + 470^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20570021 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20570029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10285010 + 10285011.

It is an arithmetic number, because the mean of its divisors is an integer number (10285011).

Almost surely, 2^20570021 is an apocalyptic number.

It is an amenable number.

20570021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20570021 is an equidigital number, since it uses as much as digits as its factorization.

20570021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 20570021 is about 4535.4185032916. The cubic root of 20570021 is about 273.9964346775.

Adding to 20570021 its reverse (12007502), we get a palindrome (32577523).

The spelling of 20570021 in words is "twenty million, five hundred seventy thousand, twenty-one".