21011013 has 6 divisors (see below), whose sum is σ = 30349254. Its totient is φ = 14007336.

The previous prime is 21011009. The next prime is 21011033. The reversal of 21011013 is 31011012.

It can be written as a sum of positive squares in only one way, i.e., 13704804 + 7306209 = 3702^2 + 2703^2 .

It is not a de Polignac number, because 21011013 - 2² = 21011009 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 2334557 = 21011013 / (2 + 1 + 0 + 1 + 1 + 0 + 1 + 3).

It is a junction number, because it is equal to n+sod(n) for n = 21010986 and 21011004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011033) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1167270 + ... + 1167287.

It is an arithmetic number, because the mean of its divisors is an integer number (5058209).

Almost surely, 2^21011013 is an apocalyptic number.

It is an amenable number.

21011013 is a deficient number, since it is larger than the sum of its proper divisors (9338241).

21011013 is a wasteful number, since it uses less digits than its factorization.

21011013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2334563 (or 2334560 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

The square root of 21011013 is about 4583.7771542692. Note that the first 3 decimals coincide. The cubic root of 21011013 is about 275.9406378319.

Adding to 21011013 its reverse (31011012), we get a palindrome (52022025).

Subtracting 21011013 from its reverse (31011012), we obtain a palindrome (9999999).

The spelling of 21011013 in words is "twenty-one million, eleven thousand, thirteen".