21078315840 has 224 divisors, whose sum is σ = 67956013440. Its totient is φ = 5534908416.

The previous prime is 21078315749. The next prime is 21078315847. The reversal of 21078315840 is 4851387012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21078315847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18280704 + ... + 18281856.

It is an arithmetic number, because the mean of its divisors is an integer number (303375060).

Almost surely, 2^21078315840 is an apocalyptic number.

21078315840 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 21078315840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33978006720).

21078315840 is an abundant number, since it is smaller than the sum of its proper divisors (46877697600).

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

21078315840 is a wasteful number, since it uses less digits than its factorization.

21078315840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1449 (or 1439 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 39.

The spelling of 21078315840 in words is "twenty-one billion, seventy-eight million, three hundred fifteen thousand, eight hundred forty".