21407008 has 48 divisors (see below), whose sum is σ = 48492864. Its totient is φ = 9112320.

The previous prime is 21406999. The next prime is 21407011. The reversal of 21407008 is 80070412.

It is a self number, because there is not a number n which added to its sum of digits gives 21407008.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50638 + ... + 51058.

It is an arithmetic number, because the mean of its divisors is an integer number (1010268).

Almost surely, 2^21407008 is an apocalyptic number.

21407008 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 21407008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24246432).

21407008 is an abundant number, since it is smaller than the sum of its proper divisors (27085856).

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

21407008 is a wasteful number, since it uses less digits than its factorization.

21407008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 665 (or 657 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 21407008 is about 4626.7707961385. The cubic root of 21407008 is about 277.6634126659.

The spelling of 21407008 in words is "twenty-one million, four hundred seven thousand, eight".