21515484 has 12 divisors (see below), whose sum is σ = 50202824. Its totient is φ = 7171824.

The previous prime is 21515479. The next prime is 21515513. The reversal of 21515484 is 48451512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 896467 + ... + 896490.

Almost surely, 2^21515484 is an apocalyptic number.

It is an amenable number.

21515484 is an abundant number, since it is smaller than the sum of its proper divisors (28687340).

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

21515484 is a wasteful number, since it uses less digits than its factorization.

21515484 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1792964 (or 1792962 counting only the distinct ones).

The product of its digits is 6400, while the sum is 30.

The square root of 21515484 is about 4638.4786298958. The cubic root of 21515484 is about 278.1316251252.

Adding to 21515484 its reverse (48451512), we get a palindrome (69966996).

The spelling of 21515484 in words is "twenty-one million, five hundred fifteen thousand, four hundred eighty-four".