20447178457 has 4 divisors (see below), whose sum is σ = 21336186240. Its totient is φ = 19558170676.

The previous prime is 20447178419. The next prime is 20447178461. The reversal of 20447178457 is 75487174402.

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.

It is a cyclic number.

It is not a de Polignac number, because 20447178457 - 2²⁷ = 20312960729 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20447178457.

It is not an unprimeable number, because it can be changed into a prime (20447172457) 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, 444503857 + ... + 444503902.

It is an arithmetic number, because the mean of its divisors is an integer number (5334046560).

Almost surely, 2^20447178457 is an apocalyptic number.

It is an amenable number.

20447178457 is a deficient number, since it is larger than the sum of its proper divisors (889007783).

20447178457 is an equidigital number, since it uses as much as digits as its factorization.

20447178457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 889007782.

The product of its (nonzero) digits is 1756160, while the sum is 49.

The spelling of 20447178457 in words is "twenty billion, four hundred forty-seven million, one hundred seventy-eight thousand, four hundred fifty-seven".