21116240 has 20 divisors (see below), whose sum is σ = 49095444. Its totient is φ = 8446464.

The previous prime is 21116219. The next prime is 21116257. The reversal of 21116240 is 4261112.

It can be written as a sum of positive squares in 2 ways, for example, as 15936064 + 5180176 = 3992^2 + 2276^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

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, 131897 + ... + 132056.

Almost surely, 2^21116240 is an apocalyptic number.

21116240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21116240 is an abundant number, since it is smaller than the sum of its proper divisors (27979204).

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

21116240 is a wasteful number, since it uses less digits than its factorization.

21116240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263966 (or 263960 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21116240 is about 4595.2410165300. The cubic root of 21116240 is about 276.4005246970.

Adding to 21116240 its reverse (4261112), we get a palindrome (25377352).

The spelling of 21116240 in words is "twenty-one million, one hundred sixteen thousand, two hundred forty".