21544315220 has 24 divisors (see below), whose sum is σ = 47904419304. Its totient is φ = 8110800896.

The previous prime is 21544315207. The next prime is 21544315279. The reversal of 21544315220 is 2251344512.

It can be written as a sum of positive squares in 4 ways, for example, as 10779007684 + 10765307536 = 103822^2 + 103756^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31682477 + ... + 31683156.

It is an arithmetic number, because the mean of its divisors is an integer number (1996017471).

Almost surely, 2^21544315220 is an apocalyptic number.

21544315220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21544315220 is an abundant number, since it is smaller than the sum of its proper divisors (26360104084).

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

21544315220 is a wasteful number, since it uses less digits than its factorization.

21544315220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63365659 (or 63365657 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 21544315220 its reverse (2251344512), we get a palindrome (23795659732).

The spelling of 21544315220 in words is "twenty-one billion, five hundred forty-four million, three hundred fifteen thousand, two hundred twenty".