21163316156520 has 128 divisors (see below), whose sum is σ = 66853552348800. Its totient is φ = 5344759766016.

The previous prime is 21163316156509. The next prime is 21163316156527. The reversal of 21163316156520 is 2565161336112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21163316156527) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5396182 + ... + 8452538.

It is an arithmetic number, because the mean of its divisors is an integer number (522293377725).

Almost surely, 2^{21163316156520} is an apocalyptic number.

21163316156520 is a gapful number since it is divisible by the number (20) 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 21163316156520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33426776174400).

21163316156520 is an abundant number, since it is smaller than the sum of its proper divisors (45690236192280).

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

21163316156520 is a wasteful number, since it uses less digits than its factorization.

21163316156520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3059427 (or 3059423 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 42.

The spelling of 21163316156520 in words is "twenty-one trillion, one hundred sixty-three billion, three hundred sixteen million, one hundred fifty-six thousand, five hundred twenty".