21460240 has 20 divisors (see below), whose sum is σ = 49895244. Its totient is φ = 8584064.

The previous prime is 21460237. The next prime is 21460331. The reversal of 21460240 is 4206412.

It can be written as a sum of positive squares in 2 ways, for example, as 5683456 + 15776784 = 2384^2 + 3972^2 .

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

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, 134047 + ... + 134206.

Almost surely, 2^21460240 is an apocalyptic number.

21460240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21460240 is an abundant number, since it is smaller than the sum of its proper divisors (28435004).

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

21460240 is a wasteful number, since it uses less digits than its factorization.

21460240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268266 (or 268260 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21460240 is about 4632.5198326613. The cubic root of 21460240 is about 277.8933738737.

Adding to 21460240 its reverse (4206412), we get a palindrome (25666652).

The spelling of 21460240 in words is "twenty-one million, four hundred sixty thousand, two hundred forty".