20021817816 has 384 divisors, whose sum is σ = 75510489600. Its totient is φ = 4799969280.

The previous prime is 20021817793. The next prime is 20021817817. The reversal of 20021817816 is 61871812002.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021817817) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1940800 + ... + 1951088.

It is an arithmetic number, because the mean of its divisors is an integer number (196641900).

Almost surely, 2^20021817816 is an apocalyptic number.

20021817816 is a gapful number since it is divisible by the number (26) 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 20021817816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37755244800).

20021817816 is an abundant number, since it is smaller than the sum of its proper divisors (55488671784).

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

20021817816 is a wasteful number, since it uses less digits than its factorization.

20021817816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10341 (or 10325 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The spelling of 20021817816 in words is "twenty billion, twenty-one million, eight hundred seventeen thousand, eight hundred sixteen".