21213007 has 4 divisors (see below), whose sum is σ = 21944520. Its totient is φ = 20481496.

The previous prime is 21212993. The next prime is 21213011. The reversal of 21213007 is 70031212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21213007 - 2¹⁵ = 21180239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213047) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365713 + ... + 365770.

It is an arithmetic number, because the mean of its divisors is an integer number (5486130).

Almost surely, 2^21213007 is an apocalyptic number.

21213007 is a deficient number, since it is larger than the sum of its proper divisors (731513).

21213007 is an equidigital number, since it uses as much as digits as its factorization.

21213007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 731512.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21213007 is about 4605.7580266445. The cubic root of 21213007 is about 276.8220911832.

Adding to 21213007 its reverse (70031212), we get a palindrome (91244219).

The spelling of 21213007 in words is "twenty-one million, two hundred thirteen thousand, seven".