21010540 has 24 divisors (see below), whose sum is σ = 44241120. Its totient is φ = 8381568.

The previous prime is 21010519. The next prime is 21010543. The reversal of 21010540 is 4501012.

It is a self number, because there is not a number n which added to its sum of digits gives 21010540.

It is not an unprimeable number, because it can be changed into a prime (21010543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7584 + ... + 9976.

It is an arithmetic number, because the mean of its divisors is an integer number (1843380).

Almost surely, 2^21010540 is an apocalyptic number.

21010540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21010540 is an abundant number, since it is smaller than the sum of its proper divisors (23230580).

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

21010540 is a wasteful number, since it uses less digits than its factorization.

21010540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2841 (or 2839 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21010540 is about 4583.7255589749. The cubic root of 21010540 is about 275.9385671575.

Adding to 21010540 its reverse (4501012), we get a palindrome (25511552).

The spelling of 21010540 in words is "twenty-one million, ten thousand, five hundred forty".