21042808 has 8 divisors (see below), whose sum is σ = 39455280. Its totient is φ = 10521400.

The previous prime is 21042803. The next prime is 21042829. The reversal of 21042808 is 80824012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1315168 + ... + 1315183.

It is an arithmetic number, because the mean of its divisors is an integer number (4931910).

Almost surely, 2^21042808 is an apocalyptic number.

It is an amenable number.

21042808 is a deficient number, since it is larger than the sum of its proper divisors (18412472).

21042808 is a wasteful number, since it uses less digits than its factorization.

21042808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2630357 (or 2630353 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 21042808 is about 4587.2440528056. The cubic root of 21042808 is about 276.0797571082.

The spelling of 21042808 in words is "twenty-one million, forty-two thousand, eight hundred eight".