21560013 has 20 divisors (see below), whose sum is σ = 32408640. Its totient is φ = 14283432.

The previous prime is 21560009. The next prime is 21560017. The reversal of 21560013 is 31006512.

It is an interprime number because it is at equal distance from previous prime (21560009) and next prime (21560017).

It is not a de Polignac number, because 21560013 - 2² = 21560009 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21560017) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 13756 + ... + 15242.

It is an arithmetic number, because the mean of its divisors is an integer number (1620432).

Almost surely, 2^21560013 is an apocalyptic number.

It is an amenable number.

21560013 is a deficient number, since it is larger than the sum of its proper divisors (10848627).

21560013 is a wasteful number, since it uses less digits than its factorization.

21560013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1678 (or 1669 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21560013 is about 4643.2761063714. The cubic root of 21560013 is about 278.3233690323.

Adding to 21560013 its reverse (31006512), we get a palindrome (52566525).

The spelling of 21560013 in words is "twenty-one million, five hundred sixty thousand, thirteen".