21009990477504 has 448 divisors, whose sum is σ = 67389916446720. Its totient is φ = 5647479889920.

The previous prime is 21009990477491. The next prime is 21009990477521. The reversal of 21009990477504 is 40577409990012.

It is a tau number, because it is divible by the number of its divisors (448).

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 63 ways as a sum of consecutive naturals, for example, 525453097 + ... + 525493079.

It is an arithmetic number, because the mean of its divisors is an integer number (150423920640).

Almost surely, 2^{21009990477504} is an apocalyptic number.

21009990477504 is a gapful number since it is divisible by the number (24) 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 21009990477504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33694958223360).

21009990477504 is an abundant number, since it is smaller than the sum of its proper divisors (46379925969216).

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

21009990477504 is a wasteful number, since it uses less digits than its factorization.

21009990477504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40308 (or 40298 counting only the distinct ones).

The product of its (nonzero) digits is 5715360, while the sum is 57.

The spelling of 21009990477504 in words is "twenty-one trillion, nine billion, nine hundred ninety million, four hundred seventy-seven thousand, five hundred four".