20557643478 has 16 divisors (see below), whose sum is σ = 42902908416. Its totient is φ = 6554610920.

The previous prime is 20557643471. The next prime is 20557643507. The reversal of 20557643478 is 87434675502.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 20557643478.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20557643471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74484078 + ... + 74484353.

It is an arithmetic number, because the mean of its divisors is an integer number (2681431776).

Almost surely, 2^20557643478 is an apocalyptic number.

20557643478 is an abundant number, since it is smaller than the sum of its proper divisors (22345264938).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20557643478 is a wasteful number, since it uses less digits than its factorization.

20557643478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148968459.

The product of its (nonzero) digits is 5644800, while the sum is 51.

The spelling of 20557643478 in words is "twenty billion, five hundred fifty-seven million, six hundred forty-three thousand, four hundred seventy-eight".