21172620061824 has 384 divisors, whose sum is σ = 71450290667520. Its totient is φ = 5493134223360.

The previous prime is 21172620061787. The next prime is 21172620061849. The reversal of 21172620061824 is 42816002627112.

It is a tau number, because it is divible by the number of its divisors (384).

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 183530049 + ... + 183645375.

It is an arithmetic number, because the mean of its divisors is an integer number (186068465280).

Almost surely, 2^{21172620061824} is an apocalyptic number.

21172620061824 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 21172620061824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35725145333760).

21172620061824 is an abundant number, since it is smaller than the sum of its proper divisors (50277670605696).

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

21172620061824 is a wasteful number, since it uses less digits than its factorization.

21172620061824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116256 (or 116237 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 42.

Adding to 21172620061824 its reverse (42816002627112), we get a palindrome (63988622688936).

The spelling of 21172620061824 in words is "twenty-one trillion, one hundred seventy-two billion, six hundred twenty million, sixty-one thousand, eight hundred twenty-four".