21542240000 has 90 divisors (see below), whose sum is σ = 53733612240. Its totient is φ = 8616832000.

The previous prime is 21542239963. The next prime is 21542240003. The reversal of 21542240000 is 4224512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542240003) by changing a digit.

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 9 ways as a sum of consecutive naturals, for example, 92681 + ... + 227319.

It is an arithmetic number, because the mean of its divisors is an integer number (597040136).

Almost surely, 2^21542240000 is an apocalyptic number.

21542240000 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 21542240000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26866806120).

21542240000 is an abundant number, since it is smaller than the sum of its proper divisors (32191372240).

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

21542240000 is an frugal number, since it uses more digits than its factorization.

21542240000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134675 (or 134646 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

Adding to 21542240000 its reverse (4224512), we get a palindrome (21546464512).

The spelling of 21542240000 in words is "twenty-one billion, five hundred forty-two million, two hundred forty thousand".