21060540 has 96 divisors (see below), whose sum is σ = 67119360. Its totient is φ = 5479488.

The previous prime is 21060539. The next prime is 21060541. The reversal of 21060540 is 4506012.

It is a happy number.

21060540 is a `hidden beast` number, since 21 + 0 + 605 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (21060539) and next prime (21060541).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21060541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22767 + ... + 23673.

It is an arithmetic number, because the mean of its divisors is an integer number (699160).

Almost surely, 2^21060540 is an apocalyptic number.

21060540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21060540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33559680).

21060540 is an abundant number, since it is smaller than the sum of its proper divisors (46058820).

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

21060540 is a wasteful number, since it uses less digits than its factorization.

21060540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 968 (or 960 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21060540 is about 4589.1763966969. The cubic root of 21060540 is about 276.1572827538.

Adding to 21060540 its reverse (4506012), we get a palindrome (25566552).

The spelling of 21060540 in words is "twenty-one million, sixty thousand, five hundred forty".