21270540 has 48 divisors (see below), whose sum is σ = 59764320. Its totient is φ = 5652480.

The previous prime is 21270539. The next prime is 21270547. The reversal of 21270540 is 4507212.

It is not an unprimeable number, because it can be changed into a prime (21270547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27276 + ... + 28044.

It is an arithmetic number, because the mean of its divisors is an integer number (1245090).

Almost surely, 2^21270540 is an apocalyptic number.

21270540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21270540 is an abundant number, since it is smaller than the sum of its proper divisors (38493780).

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

21270540 is a wasteful number, since it uses less digits than its factorization.

21270540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242 (or 1240 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21270540 is about 4611.9995663486. Note that the first 3 decimals coincide. The cubic root of 21270540 is about 277.0721269078.

Adding to 21270540 its reverse (4507212), we get a palindrome (25777752).

The spelling of 21270540 in words is "twenty-one million, two hundred seventy thousand, five hundred forty".