21510755448 has 64 divisors (see below), whose sum is σ = 66186946560. Its totient is φ = 5673165696.

The previous prime is 21510755443. The next prime is 21510755521. The reversal of 21510755448 is 84455701512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21510755443) 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 15 ways as a sum of consecutive naturals, for example, 4922440 + ... + 4926807.

It is an arithmetic number, because the mean of its divisors is an integer number (1034171040).

Almost surely, 2^21510755448 is an apocalyptic number.

21510755448 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21510755448 is an abundant number, since it is smaller than the sum of its proper divisors (44676191112).

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

21510755448 is a wasteful number, since it uses less digits than its factorization.

21510755448 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9849276 (or 9849272 counting only the distinct ones).

The product of its (nonzero) digits is 224000, while the sum is 42.

The spelling of 21510755448 in words is "twenty-one billion, five hundred ten million, seven hundred fifty-five thousand, four hundred forty-eight".