11821638820 has 24 divisors (see below), whose sum is σ = 24856086528. Its totient is φ = 4722818400.

The previous prime is 11821638799. The next prime is 11821638821. The reversal of 11821638820 is 2883612811.

It is a super-2 number, since 2×11821638820² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (11821638821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 348196 + ... + 380635.

It is an arithmetic number, because the mean of its divisors is an integer number (1035670272).

Almost surely, 2^11821638820 is an apocalyptic number.

11821638820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

11821638820 is an abundant number, since it is smaller than the sum of its proper divisors (13034447708).

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

11821638820 is a wasteful number, since it uses less digits than its factorization.

11821638820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729651 (or 729649 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 40.

The spelling of 11821638820 in words is "eleven billion, eight hundred twenty-one million, six hundred thirty-eight thousand, eight hundred twenty".