21420312220 has 12 divisors (see below), whose sum is σ = 44982655704. Its totient is φ = 8568124880.

The previous prime is 21420312197. The next prime is 21420312223. The reversal of 21420312220 is 2221302412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420312223) 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, 535507786 + ... + 535507825.

It is an arithmetic number, because the mean of its divisors is an integer number (3748554642).

Almost surely, 2^21420312220 is an apocalyptic number.

21420312220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21420312220 is an abundant number, since it is smaller than the sum of its proper divisors (23562343484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21420312220 is a wasteful number, since it uses less digits than its factorization.

21420312220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071015620 (or 1071015618 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21420312220 its reverse (2221302412), we get a palindrome (23641614632).

The spelling of 21420312220 in words is "twenty-one billion, four hundred twenty million, three hundred twelve thousand, two hundred twenty".