20447240257 has 4 divisors (see below), whose sum is σ = 20945953476. Its totient is φ = 19948527040.

The previous prime is 20447240201. The next prime is 20447240267. The reversal of 20447240257 is 75204274402.

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 2572619841 + 17874620416 = 50721^2 + 133696^2 .

It is not a de Polignac number, because 20447240257 - 2¹⁵ = 20447207489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20447240267) 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, 249356548 + ... + 249356629.

It is an arithmetic number, because the mean of its divisors is an integer number (5236488369).

Almost surely, 2^20447240257 is an apocalyptic number.

It is an amenable number.

20447240257 is a deficient number, since it is larger than the sum of its proper divisors (498713219).

20447240257 is an equidigital number, since it uses as much as digits as its factorization.

20447240257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 498713218.

The product of its (nonzero) digits is 125440, while the sum is 37.

The spelling of 20447240257 in words is "twenty billion, four hundred forty-seven million, two hundred forty thousand, two hundred fifty-seven".