21156163863552 has 880 divisors, whose sum is σ = 68387529967680. Its totient is φ = 6510758952960.

The previous prime is 21156163863547. The next prime is 21156163863553. The reversal of 21156163863552 is 25536836165112.

21156163863552 is a `hidden beast` number, since 2 + 1 + 1 + 5 + 6 + 1 + 6 + 3 + 86 + 3 + 552 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (7776000) is a multiple of the sum of its prime divisors (972).

It is not an unprimeable number, because it can be changed into a prime (21156163863553) by changing a digit.

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 79 ways as a sum of consecutive naturals, for example, 23325428283 + ... + 23325429189.

It is an arithmetic number, because the mean of its divisors is an integer number (77713102236).

Almost surely, 2^{21156163863552} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21156163863552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34193764983840).

21156163863552 is an abundant number, since it is smaller than the sum of its proper divisors (47231366104128).

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

21156163863552 is an frugal number, since it uses more digits than its factorization.

21156163863552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1037 (or 972 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 54.

The spelling of 21156163863552 in words is "twenty-one trillion, one hundred fifty-six billion, one hundred sixty-three million, eight hundred sixty-three thousand, five hundred fifty-two".