21520112087 has 4 divisors (see below), whose sum is σ = 22101736776. Its totient is φ = 20938487400.

The previous prime is 21520112071. The next prime is 21520112093. The reversal of 21520112087 is 78021102512.

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 21520112087 - 2⁴ = 21520112071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520112017) 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, 290812289 + ... + 290812362.

It is an arithmetic number, because the mean of its divisors is an integer number (5525434194).

Almost surely, 2^21520112087 is an apocalyptic number.

21520112087 is a deficient number, since it is larger than the sum of its proper divisors (581624689).

21520112087 is an equidigital number, since it uses as much as digits as its factorization.

21520112087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581624688.

The product of its (nonzero) digits is 2240, while the sum is 29.

Adding to 21520112087 its reverse (78021102512), we get a palindrome (99541214599).

The spelling of 21520112087 in words is "twenty-one billion, five hundred twenty million, one hundred twelve thousand, eighty-seven".