7821721600 has 432 divisors, whose sum is σ = 24964402176. Its totient is φ = 2359296000.

The previous prime is 7821721561. The next prime is 7821721639. The reversal of 7821721600 is 61271287.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (7821721561) and next prime (7821721639).

It is a super-2 number, since 2×7821721600² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 252313585 + ... + 252313615.

It is an arithmetic number, because the mean of its divisors is an integer number (57787968).

Almost surely, 2^7821721600 is an apocalyptic number.

7821721600 is a gapful number since it is divisible by the number (70) 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 7821721600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12482201088).

7821721600 is an abundant number, since it is smaller than the sum of its proper divisors (17142680576).

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

7821721600 is an equidigital number, since it uses as much as digits as its factorization.

7821721600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93 (or 56 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 34.

The square root of 7821721600 is about 88440.4975110385. The cubic root of 7821721600 is about 1985.0317214548.

Adding to 7821721600 its reverse (61271287), we get a palindrome (7882992887).

The spelling of 7821721600 in words is "seven billion, eight hundred twenty-one million, seven hundred twenty-one thousand, six hundred".