20578478761523 has 4 divisors (see below), whose sum is σ = 21242300657088. Its totient is φ = 19914656865960.

The previous prime is 20578478761517. The next prime is 20578478761537. The reversal of 20578478761523 is 32516787487502.

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

It is a cyclic number.

It is not a de Polignac number, because 20578478761523 - 2²⁴ = 20578461984307 is a prime.

It is a super-3 number, since 3×20578478761523³ (a number of 41 digits) contains 333 as substring.

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 20578478761523.

It is not an unprimeable number, because it can be changed into a prime (20578478761573) 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, 331910947736 + ... + 331910947797.

It is an arithmetic number, because the mean of its divisors is an integer number (5310575164272).

Almost surely, 2^{20578478761523} is an apocalyptic number.

20578478761523 is a deficient number, since it is larger than the sum of its proper divisors (663821895565).

20578478761523 is an equidigital number, since it uses as much as digits as its factorization.

20578478761523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 663821895564.

The product of its (nonzero) digits is 158054400, while the sum is 65.

The spelling of 20578478761523 in words is "twenty trillion, five hundred seventy-eight billion, four hundred seventy-eight million, seven hundred sixty-one thousand, five hundred twenty-three".