7891199820 has 120 divisors (see below), whose sum is σ = 28291453344. Its totient is φ = 1803700224.

The previous prime is 7891199819. The next prime is 7891199821. The reversal of 7891199820 is 289911987.

It is an interprime number because it is at equal distance from previous prime (7891199819) and next prime (7891199821).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (7891199821) by changing a digit.

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 39 ways as a sum of consecutive naturals, for example, 336597 + ... + 359276.

Almost surely, 2^7891199820 is an apocalyptic number.

7891199820 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

7891199820 is an abundant number, since it is smaller than the sum of its proper divisors (20400253524).

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

7891199820 is a wasteful number, since it uses less digits than its factorization.

7891199820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695901 (or 695890 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 54.

The square root of 7891199820 is about 88832.4254988008. The cubic root of 7891199820 is about 1990.8919025794.

The spelling of 7891199820 in words is "seven billion, eight hundred ninety-one million, one hundred ninety-nine thousand, eight hundred twenty".