21515640344 has 16 divisors (see below), whose sum is σ = 44009264520. Its totient is φ = 9779836480.

The previous prime is 21515640343. The next prime is 21515640353. The reversal of 21515640344 is 44304651512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21515640343) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122247869 + ... + 122248044.

Almost surely, 2^21515640344 is an apocalyptic number.

It is an amenable number.

21515640344 is an abundant number, since it is smaller than the sum of its proper divisors (22493624176).

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

21515640344 is a wasteful number, since it uses less digits than its factorization.

21515640344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244495930 (or 244495926 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 35.

The spelling of 21515640344 in words is "twenty-one billion, five hundred fifteen million, six hundred forty thousand, three hundred forty-four".