21044340540 has 48 divisors (see below), whose sum is σ = 65471283360. Its totient is φ = 5611824000.

The previous prime is 21044340539. The next prime is 21044340553. The reversal of 21044340540 is 4504344012.

It is a happy number.

21044340540 is a `hidden beast` number, since 210 + 4 + 4 + 3 + 405 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19484961 + ... + 19486040.

It is an arithmetic number, because the mean of its divisors is an integer number (1363985070).

Almost surely, 2^21044340540 is an apocalyptic number.

21044340540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21044340540 is an abundant number, since it is smaller than the sum of its proper divisors (44426942820).

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

21044340540 is a wasteful number, since it uses less digits than its factorization.

21044340540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38971019 (or 38971011 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

Adding to 21044340540 its reverse (4504344012), we get a palindrome (25548684552).

The spelling of 21044340540 in words is "twenty-one billion, forty-four million, three hundred forty thousand, five hundred forty".