21404016 has 30 divisors (see below), whose sum is σ = 59901920. Its totient is φ = 7134624.

The previous prime is 21403979. The next prime is 21404017. The reversal of 21404016 is 61040412.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a self number, because there is not a number n which added to its sum of digits gives 21404016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 74176 + ... + 74463.

Almost surely, 2^21404016 is an apocalyptic number.

It is an amenable number.

21404016 is an abundant number, since it is smaller than the sum of its proper divisors (38497904).

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

21404016 is a wasteful number, since it uses less digits than its factorization.

21404016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148653 (or 148644 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21404016 is about 4626.4474491774. The cubic root of 21404016 is about 277.6504759734.

Adding to 21404016 its reverse (61040412), we get a palindrome (82444428).

The spelling of 21404016 in words is "twenty-one million, four hundred four thousand, sixteen".