21399875840 has 216 divisors, whose sum is σ = 60649404480. Its totient is φ = 7211495424.

The previous prime is 21399875813. The next prime is 21399875843. The reversal of 21399875840 is 4857899312.

It is a Harshad number since it is a multiple of its sum of digits (56).

It is not an unprimeable number, because it can be changed into a prime (21399875843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3697589 + ... + 3703371.

It is an arithmetic number, because the mean of its divisors is an integer number (280784280).

Almost surely, 2^21399875840 is an apocalyptic number.

21399875840 is a gapful number since it is divisible by the number (20) 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 21399875840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30324702240).

21399875840 is an abundant number, since it is smaller than the sum of its proper divisors (39249528640).

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

21399875840 is an equidigital number, since it uses as much as digits as its factorization.

21399875840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5877 (or 5856 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 56.

The spelling of 21399875840 in words is "twenty-one billion, three hundred ninety-nine million, eight hundred seventy-five thousand, eight hundred forty".