20538257 has 4 divisors (see below), whose sum is σ = 20548080. Its totient is φ = 20528436.

The previous prime is 20538239. The next prime is 20538283. The reversal of 20538257 is 75283502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20538257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20538157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 383 + ... + 6420.

It is an arithmetic number, because the mean of its divisors is an integer number (5137020).

Almost surely, 2^20538257 is an apocalyptic number.

It is an amenable number.

20538257 is a deficient number, since it is larger than the sum of its proper divisors (9823).

20538257 is an equidigital number, since it uses as much as digits as its factorization.

20538257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9822.

The product of its (nonzero) digits is 16800, while the sum is 32.

The square root of 20538257 is about 4531.9153787334. The cubic root of 20538257 is about 273.8553279280.

The spelling of 20538257 in words is "twenty million, five hundred thirty-eight thousand, two hundred fifty-seven".