21000213 has 24 divisors (see below), whose sum is σ = 32847360. Its totient is φ = 12852000.

The previous prime is 21000193. The next prime is 21000229. The reversal of 21000213 is 31200012.

It is a happy number.

It is not a de Polignac number, because 21000213 - 2¹² = 20996117 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21000195 and 21000204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000233) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27588 + ... + 28338.

It is an arithmetic number, because the mean of its divisors is an integer number (1368640).

Almost surely, 2^21000213 is an apocalyptic number.

It is an amenable number.

21000213 is a deficient number, since it is larger than the sum of its proper divisors (11847147).

21000213 is a wasteful number, since it uses less digits than its factorization.

21000213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1009 (or 1006 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21000213 is about 4582.5989351022. The cubic root of 21000213 is about 275.8933504141.

Adding to 21000213 its reverse (31200012), we get a palindrome (52200225).

The spelling of 21000213 in words is "twenty-one million, two hundred thirteen", and thus it is an aban number.