21210223540 has 48 divisors (see below), whose sum is σ = 48701600640. Its totient is φ = 7695204480.

The previous prime is 21210223537. The next prime is 21210223549. The reversal of 21210223540 is 4532201212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210223549) 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 15 ways as a sum of consecutive naturals, for example, 13227 + ... + 206386.

It is an arithmetic number, because the mean of its divisors is an integer number (1014616680).

Almost surely, 2^21210223540 is an apocalyptic number.

21210223540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21210223540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24350800320).

21210223540 is an abundant number, since it is smaller than the sum of its proper divisors (27491377100).

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

21210223540 is a wasteful number, since it uses less digits than its factorization.

21210223540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220072 (or 220070 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

Adding to 21210223540 its reverse (4532201212), we get a palindrome (25742424752).

The spelling of 21210223540 in words is "twenty-one billion, two hundred ten million, two hundred twenty-three thousand, five hundred forty".