21103240 has 16 divisors (see below), whose sum is σ = 47482380. Its totient is φ = 8441280.

The previous prime is 21103217. The next prime is 21103241. The reversal of 21103240 is 4230112.

It can be written as a sum of positive squares in 2 ways, for example, as 20593444 + 509796 = 4538^2 + 714^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21103240.

It is not an unprimeable number, because it can be changed into a prime (21103241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 263751 + ... + 263830.

Almost surely, 2^21103240 is an apocalyptic number.

21103240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21103240 is an abundant number, since it is smaller than the sum of its proper divisors (26379140).

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

21103240 is a wasteful number, since it uses less digits than its factorization.

21103240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527592 (or 527588 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21103240 is about 4593.8262918835. The cubic root of 21103240 is about 276.3437919888.

Adding to 21103240 its reverse (4230112), we get a palindrome (25333352).

The spelling of 21103240 in words is "twenty-one million, one hundred three thousand, two hundred forty".