20857817568 has 288 divisors, whose sum is σ = 66658443264. Its totient is φ = 5592996864.

The previous prime is 20857817557. The next prime is 20857817569. The reversal of 20857817568 is 86571875802.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857817569) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 30808846 + ... + 30809522.

It is an arithmetic number, because the mean of its divisors is an integer number (231452928).

Almost surely, 2^20857817568 is an apocalyptic number.

20857817568 is a gapful number since it is divisible by the number (28) 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 20857817568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33329221632).

20857817568 is an abundant number, since it is smaller than the sum of its proper divisors (45800625696).

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

20857817568 is a wasteful number, since it uses less digits than its factorization.

20857817568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862 (or 835 counting only the distinct ones).

The product of its (nonzero) digits is 7526400, while the sum is 57.

The spelling of 20857817568 in words is "twenty billion, eight hundred fifty-seven million, eight hundred seventeen thousand, five hundred sixty-eight".