21016920 has 32 divisors (see below), whose sum is σ = 63051120. Its totient is φ = 5604480.

The previous prime is 21016903. The next prime is 21016949. The reversal of 21016920 is 2961012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87451 + ... + 87690.

Almost surely, 2^21016920 is an apocalyptic number.

21016920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21016920 is an abundant number, since it is smaller than the sum of its proper divisors (42034200).

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

21016920 is a wasteful number, since it uses less digits than its factorization.

21016920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175155 (or 175151 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 21016920 is about 4584.4214465950. The cubic root of 21016920 is about 275.9664945675.

Adding to 21016920 its reverse (2961012), we get a palindrome (23977932).

The spelling of 21016920 in words is "twenty-one million, sixteen thousand, nine hundred twenty".