7321681920 has 480 divisors, whose sum is σ = 28689012000. Its totient is φ = 1585446912.

The previous prime is 7321681909. The next prime is 7321681933. The reversal of 7321681920 is 291861237.

It is a tau number, because it is divible by the number of its divisors (480).

It is a super-2 number, since 2×7321681920² (a number of 21 digits) contains 22 as substring.

It is a nialpdrome in base 8.

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, 385351671 + ... + 385351689.

It is an arithmetic number, because the mean of its divisors is an integer number (59768775).

Almost surely, 2^7321681920 is an apocalyptic number.

7321681920 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 7321681920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14344506000).

7321681920 is an abundant number, since it is smaller than the sum of its proper divisors (21367330080).

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

7321681920 is an frugal number, since it uses more digits than its factorization.

7321681920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 7321681920 is about 85566.8272170939. The cubic root of 7321681920 is about 1941.7960764094.

The spelling of 7321681920 in words is "seven billion, three hundred twenty-one million, six hundred eighty-one thousand, nine hundred twenty".