21013015 has 8 divisors (see below), whose sum is σ = 25240320. Its totient is φ = 16793952.

The previous prime is 21012997. The next prime is 21013019. The reversal of 21013015 is 51031012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21013015 - 2⁹ = 21012503 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21012986 and 21013004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8266 + ... + 10504.

It is an arithmetic number, because the mean of its divisors is an integer number (3155040).

Almost surely, 2^21013015 is an apocalyptic number.

21013015 is a deficient number, since it is larger than the sum of its proper divisors (4227305).

21013015 is a wasteful number, since it uses less digits than its factorization.

21013015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4121.

The product of its (nonzero) digits is 30, while the sum is 13.

The square root of 21013015 is about 4583.9955279210. The cubic root of 21013015 is about 275.9494017376.

Adding to 21013015 its reverse (51031012), we get a palindrome (72044027).

It can be divided in two parts, 210 and 13015, that added together give a square (13225 = 115²).

The spelling of 21013015 in words is "twenty-one million, thirteen thousand, fifteen".