21420587663 has 4 divisors (see below), whose sum is σ = 21467053608. Its totient is φ = 21374121720.

The previous prime is 21420587659. The next prime is 21420587687. The reversal of 21420587663 is 36678502412.

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 21420587663 - 2² = 21420587659 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 (21420587603) 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, 23232281 + ... + 23233202.

It is an arithmetic number, because the mean of its divisors is an integer number (5366763402).

Almost surely, 2^21420587663 is an apocalyptic number.

21420587663 is a deficient number, since it is larger than the sum of its proper divisors (46465945).

21420587663 is an equidigital number, since it uses as much as digits as its factorization.

21420587663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46465944.

The product of its (nonzero) digits is 483840, while the sum is 44.

The spelling of 21420587663 in words is "twenty-one billion, four hundred twenty million, five hundred eighty-seven thousand, six hundred sixty-three".