21508016 has 20 divisors (see below), whose sum is σ = 41744352. Its totient is φ = 10735296.

The previous prime is 21507979. The next prime is 21508027. The reversal of 21508016 is 61080512.

It is a junction number, because it is equal to n+sod(n) for n = 21507982 and 21508000.

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, 15545 + ... + 16871.

Almost surely, 2^21508016 is an apocalyptic number.

It is an amenable number.

21508016 is a deficient number, since it is larger than the sum of its proper divisors (20236336).

21508016 is a wasteful number, since it uses less digits than its factorization.

21508016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348 (or 2342 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 21508016 is about 4637.6735547039. The cubic root of 21508016 is about 278.0994416778.

Adding to 21508016 its reverse (61080512), we get a palindrome (82588528).

The spelling of 21508016 in words is "twenty-one million, five hundred eight thousand, sixteen".