20423257 has 2 divisors, whose sum is σ = 20423258. Its totient is φ = 20423256.

The previous prime is 20423231. The next prime is 20423329. The reversal of 20423257 is 75232402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13111641 + 7311616 = 3621^2 + 2704^2 .

It is a cyclic number.

It is not a de Polignac number, because 20423257 - 2⁷ = 20423129 is a prime.

It is not a weakly prime, because it can be changed into another prime (20423357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10211628 + 10211629.

It is an arithmetic number, because the mean of its divisors is an integer number (10211629).

Almost surely, 2^20423257 is an apocalyptic number.

It is an amenable number.

20423257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20423257 is an equidigital number, since it uses as much as digits as its factorization.

20423257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3360, while the sum is 25.

The square root of 20423257 is about 4519.2097760560. The cubic root of 20423257 is about 273.3432376278.

Adding to 20423257 its reverse (75232402), we get a palindrome (95655659).

The spelling of 20423257 in words is "twenty million, four hundred twenty-three thousand, two hundred fifty-seven".