21078016 has 56 divisors (see below), whose sum is σ = 44037504. Its totient is φ = 10076160.

The previous prime is 21077971. The next prime is 21078053. The reversal of 21078016 is 61087012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 253911 + ... + 253993.

It is an arithmetic number, because the mean of its divisors is an integer number (786384).

Almost surely, 2^21078016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21078016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22018752).

21078016 is an abundant number, since it is smaller than the sum of its proper divisors (22959488).

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

21078016 is an frugal number, since it uses more digits than its factorization.

21078016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21078016 is about 4591.0800472220. The cubic root of 21078016 is about 276.2336465821.

The spelling of 21078016 in words is "twenty-one million, seventy-eight thousand, sixteen".