21158213 has 8 divisors (see below), whose sum is σ = 22150656. Its totient is φ = 20185200.

The previous prime is 21158201. The next prime is 21158231. The reversal of 21158213 is 31285112.

It is a happy number.

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 21158213 - 2⁸ = 21157957 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 (21158273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2606 + ... + 7007.

It is an arithmetic number, because the mean of its divisors is an integer number (2768832).

Almost surely, 2^21158213 is an apocalyptic number.

It is an amenable number.

21158213 is a deficient number, since it is larger than the sum of its proper divisors (992443).

21158213 is an equidigital number, since it uses as much as digits as its factorization.

21158213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9715.

The product of its digits is 480, while the sum is 23.

The square root of 21158213 is about 4599.8057567684. The cubic root of 21158213 is about 276.5835383551.

The spelling of 21158213 in words is "twenty-one million, one hundred fifty-eight thousand, two hundred thirteen".