21560040 has 64 divisors (see below), whose sum is σ = 71870400. Its totient is φ = 5749056.

The previous prime is 21560027. The next prime is 21560047. The reversal of 21560040 is 4006512.

It is a happy number.

21560040 is a `hidden beast` number, since 21 + 5 + 600 + 40 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21559995 and 21560022.

It is not an unprimeable number, because it can be changed into a prime (21560047) 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 15 ways as a sum of consecutive naturals, for example, 8902 + ... + 11061.

It is an arithmetic number, because the mean of its divisors is an integer number (1122975).

Almost surely, 2^21560040 is an apocalyptic number.

21560040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21560040 is an abundant number, since it is smaller than the sum of its proper divisors (50310360).

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

21560040 is a wasteful number, since it uses less digits than its factorization.

21560040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19983 (or 19973 counting only the distinct ones).

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

The square root of 21560040 is about 4643.2790138005. The cubic root of 21560040 is about 278.3234852154.

Adding to 21560040 its reverse (4006512), we get a palindrome (25566552).

The spelling of 21560040 in words is "twenty-one million, five hundred sixty thousand, forty".