21042560 has 192 divisors, whose sum is σ = 64884240. Its totient is φ = 6451200.

The previous prime is 21042551. The next prime is 21042563. The reversal of 21042560 is 6524012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042563) 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 23 ways as a sum of consecutive naturals, for example, 344930 + ... + 344990.

Almost surely, 2^21042560 is an apocalyptic number.

21042560 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 21042560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32442120).

21042560 is an abundant number, since it is smaller than the sum of its proper divisors (43841680).

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

21042560 is a wasteful number, since it uses less digits than its factorization.

21042560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21042560 is about 4587.2170212450. The cubic root of 21042560 is about 276.0786725247.

Adding to 21042560 its reverse (6524012), we get a palindrome (27566572).

It can be divided in two parts, 2104 and 2560, that added together give a palindrome (4664).

The spelling of 21042560 in words is "twenty-one million, forty-two thousand, five hundred sixty".