21187845487 has 8 divisors (see below), whose sum is σ = 21230681472. Its totient is φ = 21145036800.

The previous prime is 21187845473. The next prime is 21187845517. The reversal of 21187845487 is 78454878112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21187845487 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 (21187845587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2278287 + ... + 2287567.

It is an arithmetic number, because the mean of its divisors is an integer number (2653835184).

Almost surely, 2^21187845487 is an apocalyptic number.

21187845487 is a deficient number, since it is larger than the sum of its proper divisors (42835985).

21187845487 is an equidigital number, since it uses as much as digits as its factorization.

21187845487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13649.

The product of its digits is 4014080, while the sum is 55.

The spelling of 21187845487 in words is "twenty-one billion, one hundred eighty-seven million, eight hundred forty-five thousand, four hundred eighty-seven".