21601560 has 64 divisors (see below), whose sum is σ = 68623200. Its totient is φ = 5421056.

The previous prime is 21601519. The next prime is 21601561. The reversal of 21601560 is 6510612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21601561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3255 + ... + 7334.

Almost surely, 2^21601560 is an apocalyptic number.

21601560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21601560 is an abundant number, since it is smaller than the sum of its proper divisors (47021640).

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

21601560 is a wasteful number, since it uses less digits than its factorization.

21601560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10620 (or 10616 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21601560 is about 4647.7478416971. The cubic root of 21601560 is about 278.5020343726.

The spelling of 21601560 in words is "twenty-one million, six hundred one thousand, five hundred sixty".