21407708 has 36 divisors (see below), whose sum is σ = 43858080. Its totient is φ = 9116352.

The previous prime is 21407693. The next prime is 21407717. The reversal of 21407708 is 80770412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46616 + ... + 47072.

It is an arithmetic number, because the mean of its divisors is an integer number (1218280).

Almost surely, 2^21407708 is an apocalyptic number.

21407708 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 21407708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21929040).

21407708 is an abundant number, since it is smaller than the sum of its proper divisors (22450372).

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

21407708 is a wasteful number, since it uses less digits than its factorization.

21407708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714 (or 705 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 21407708 is about 4626.8464422325. The cubic root of 21407708 is about 277.6664391245. Note that the first 3 decimals are identical.

The spelling of 21407708 in words is "twenty-one million, four hundred seven thousand, seven hundred eight".