21404516 has 12 divisors (see below), whose sum is σ = 42809088. Its totient is φ = 9173352.

The previous prime is 21404503. The next prime is 21404531. The reversal of 21404516 is 61540412.

21404516 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21404491 and 21404500.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 382196 + ... + 382251.

It is an arithmetic number, because the mean of its divisors is an integer number (3567424).

Almost surely, 2^21404516 is an apocalyptic number.

It is an amenable number.

21404516 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21404516 is a wasteful number, since it uses less digits than its factorization.

21404516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764458 (or 764456 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21404516 is about 4626.5014860043. The cubic root of 21404516 is about 277.6526379377.

Adding to 21404516 its reverse (61540412), we get a palindrome (82944928).

The spelling of 21404516 in words is "twenty-one million, four hundred four thousand, five hundred sixteen".