20997824400 has 660 divisors, whose sum is σ = 87161500672. Its totient is φ = 4761711360.

The previous prime is 20997824399. The next prime is 20997824423. The reversal of 20997824400 is 442879902.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 131 ways as a sum of consecutive naturals, for example, 165337137 + ... + 165337263.

Almost surely, 2^20997824400 is an apocalyptic number.

20997824400 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 20997824400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43580750336).

20997824400 is an abundant number, since it is smaller than the sum of its proper divisors (66163676272).

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

20997824400 is an equidigital number, since it uses as much as digits as its factorization.

20997824400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The spelling of 20997824400 in words is "twenty billion, nine hundred ninety-seven million, eight hundred twenty-four thousand, four hundred".