21079968 has 192 divisors, whose sum is σ = 72253440. Its totient is φ = 5225472.

The previous prime is 21079931. The next prime is 21079979. The reversal of 21079968 is 86997012.

It is a Harshad number since it is a multiple of its sum of digits (42).

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, 165921 + ... + 166047.

It is an arithmetic number, because the mean of its divisors is an integer number (376320).

Almost surely, 2^21079968 is an apocalyptic number.

21079968 is a gapful number since it is divisible by the number (28) 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 21079968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36126720).

21079968 is an abundant number, since it is smaller than the sum of its proper divisors (51173472).

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

21079968 is a wasteful number, since it uses less digits than its factorization.

21079968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179 (or 171 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 21079968 is about 4591.2926284435. The cubic root of 21079968 is about 276.2421734984.

The spelling of 21079968 in words is "twenty-one million, seventy-nine thousand, nine hundred sixty-eight".