21143808 has 288 divisors, whose sum is σ = 78489600. Its totient is φ = 5474304.

The previous prime is 21143807. The next prime is 21143839. The reversal of 21143808 is 80834112.

It is a tau number, because it is divible by the number of its divisors (288).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21143807) 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, 919285 + ... + 919307.

Almost surely, 2^21143808 is an apocalyptic number.

21143808 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 21143808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39244800).

21143808 is an abundant number, since it is smaller than the sum of its proper divisors (57345792).

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

21143808 is a wasteful number, since it uses less digits than its factorization.

21143808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21143808 is about 4598.2396631755. The cubic root of 21143808 is about 276.5207559517.

The spelling of 21143808 in words is "twenty-one million, one hundred forty-three thousand, eight hundred eight".