21109384820 has 24 divisors (see below), whose sum is σ = 46257087744. Its totient is φ = 8076634016.

The previous prime is 21109384799. The next prime is 21109384841. The reversal of 21109384820 is 2848390112.

It is an interprime number because it is at equal distance from previous prime (21109384799) and next prime (21109384841).

It is a super-2 number, since 2×21109384820² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22944524 + ... + 22945443.

It is an arithmetic number, because the mean of its divisors is an integer number (1927378656).

Almost surely, 2^21109384820 is an apocalyptic number.

21109384820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21109384820 is an abundant number, since it is smaller than the sum of its proper divisors (25147702924).

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

21109384820 is a wasteful number, since it uses less digits than its factorization.

21109384820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45889999 (or 45889997 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 38.

The spelling of 21109384820 in words is "twenty-one billion, one hundred nine million, three hundred eighty-four thousand, eight hundred twenty".