12540021563 has 4 divisors (see below), whose sum is σ = 12542739888. Its totient is φ = 12537303240.

The previous prime is 12540021553. The next prime is 12540021577. The reversal of 12540021563 is 36512004521.

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 12540021563 - 2²⁰ = 12538972987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12540021523) 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, 1352231 + ... + 1361472.

It is an arithmetic number, because the mean of its divisors is an integer number (3135684972).

Almost surely, 2^12540021563 is an apocalyptic number.

12540021563 is a deficient number, since it is larger than the sum of its proper divisors (2718325).

12540021563 is an equidigital number, since it uses as much as digits as its factorization.

12540021563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2718324.

The product of its (nonzero) digits is 7200, while the sum is 29.

The spelling of 12540021563 in words is "twelve billion, five hundred forty million, twenty-one thousand, five hundred sixty-three".