21042124240 has 20 divisors (see below), whose sum is σ = 48922939044. Its totient is φ = 8416849664.

The previous prime is 21042124219. The next prime is 21042124249. The reversal of 21042124240 is 4242124012.

It can be written as a sum of positive squares in 2 ways, for example, as 14811863616 + 6230260624 = 121704^2 + 78932^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042124249) 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 3 ways as a sum of consecutive naturals, for example, 131513197 + ... + 131513356.

Almost surely, 2^21042124240 is an apocalyptic number.

21042124240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21042124240 is an abundant number, since it is smaller than the sum of its proper divisors (27880814804).

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

21042124240 is a wasteful number, since it uses less digits than its factorization.

21042124240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263026566 (or 263026560 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 22.

Adding to 21042124240 its reverse (4242124012), we get a palindrome (25284248252).

The spelling of 21042124240 in words is "twenty-one billion, forty-two million, one hundred twenty-four thousand, two hundred forty".