21428608344 has 128 divisors (see below), whose sum is σ = 64472647680. Its totient is φ = 5847782400.

The previous prime is 21428608337. The next prime is 21428608373. The reversal of 21428608344 is 44380682412.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21428608296 and 21428608305.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 64569 + ... + 216855.

It is an arithmetic number, because the mean of its divisors is an integer number (503692560).

Almost surely, 2^21428608344 is an apocalyptic number.

21428608344 is a gapful number since it is divisible by the number (24) 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 21428608344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32236323840).

21428608344 is an abundant number, since it is smaller than the sum of its proper divisors (43044039336).

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

21428608344 is a wasteful number, since it uses less digits than its factorization.

21428608344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152361 (or 152357 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 42.

The spelling of 21428608344 in words is "twenty-one billion, four hundred twenty-eight million, six hundred eight thousand, three hundred forty-four".