21055244340 has 192 divisors, whose sum is σ = 64728357120. Its totient is φ = 5082255360.

The previous prime is 21055244323. The next prime is 21055244341. The reversal of 21055244340 is 4344255012.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21055244298 and 21055244307.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055244341) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 26025856 + ... + 26026664.

It is an arithmetic number, because the mean of its divisors is an integer number (337126860).

Almost surely, 2^21055244340 is an apocalyptic number.

21055244340 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 21055244340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32364178560).

21055244340 is an abundant number, since it is smaller than the sum of its proper divisors (43673112780).

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

21055244340 is a wasteful number, since it uses less digits than its factorization.

21055244340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1442 (or 1440 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 30.

Adding to 21055244340 its reverse (4344255012), we get a palindrome (25399499352).

The spelling of 21055244340 in words is "twenty-one billion, fifty-five million, two hundred forty-four thousand, three hundred forty".