21515630563 has 4 divisors (see below), whose sum is σ = 24589292080. Its totient is φ = 18441969048.

The previous prime is 21515630519. The next prime is 21515630659. The reversal of 21515630563 is 36503651512.

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 21515630563 - 2¹³ = 21515622371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21515630863) 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 3 ways as a sum of consecutive naturals, for example, 1536830748 + ... + 1536830761.

It is an arithmetic number, because the mean of its divisors is an integer number (6147323020).

Almost surely, 2^21515630563 is an apocalyptic number.

21515630563 is a deficient number, since it is larger than the sum of its proper divisors (3073661517).

21515630563 is an equidigital number, since it uses as much as digits as its factorization.

21515630563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3073661516.

The product of its (nonzero) digits is 81000, while the sum is 37.

The spelling of 21515630563 in words is "twenty-one billion, five hundred fifteen million, six hundred thirty thousand, five hundred sixty-three".