21011213 has 8 divisors (see below), whose sum is σ = 22009536. Its totient is φ = 20020000.

The previous prime is 21011191. The next prime is 21011231. The reversal of 21011213 is 31211012.

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 21011213 - 2¹⁰ = 21010189 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21011194 and 21011203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011233) 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, 4838 + ... + 8088.

It is an arithmetic number, because the mean of its divisors is an integer number (2751192).

Almost surely, 2^21011213 is an apocalyptic number.

21011213 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21011213 is a deficient number, since it is larger than the sum of its proper divisors (998323).

21011213 is a wasteful number, since it uses less digits than its factorization.

21011213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3555.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21011213 is about 4583.7989702865. The cubic root of 21011213 is about 275.9415133720.

Adding to 21011213 its reverse (31211012), we get a palindrome (52222225).

The spelling of 21011213 in words is "twenty-one million, eleven thousand, two hundred thirteen".