20557256449 has 4 divisors (see below), whose sum is σ = 20558183940. Its totient is φ = 20556328960.

The previous prime is 20557256437. The next prime is 20557256471. The reversal of 20557256449 is 94465275502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8348111424 + 12209145025 = 91368^2 + 110495^2 .

It is a cyclic number.

It is not a de Polignac number, because 20557256449 - 2¹¹ = 20557254401 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20557256429) 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, 429664 + ... + 475105.

It is an arithmetic number, because the mean of its divisors is an integer number (5139545985).

Almost surely, 2^20557256449 is an apocalyptic number.

It is an amenable number.

20557256449 is a deficient number, since it is larger than the sum of its proper divisors (927491).

20557256449 is an equidigital number, since it uses as much as digits as its factorization.

20557256449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927490.

The product of its (nonzero) digits is 3024000, while the sum is 49.

The spelling of 20557256449 in words is "twenty billion, five hundred fifty-seven million, two hundred fifty-six thousand, four hundred forty-nine".