21702421087 has 4 divisors (see below), whose sum is σ = 21727569600. Its totient is φ = 21677272576.

The previous prime is 21702421043. The next prime is 21702421171. The reversal of 21702421087 is 78012420712.

It is a happy number.

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 21702421087 - 2⁷ = 21702420959 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 (21702421387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12572962 + ... + 12574687.

It is an arithmetic number, because the mean of its divisors is an integer number (5431892400).

Almost surely, 2^21702421087 is an apocalyptic number.

21702421087 is a deficient number, since it is larger than the sum of its proper divisors (25148513).

21702421087 is an equidigital number, since it uses as much as digits as its factorization.

21702421087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25148512.

The product of its (nonzero) digits is 12544, while the sum is 34.

Adding to 21702421087 its reverse (78012420712), we get a palindrome (99714841799).

The spelling of 21702421087 in words is "twenty-one billion, seven hundred two million, four hundred twenty-one thousand, eighty-seven".