21168213 has 32 divisors (see below), whose sum is σ = 33022080. Its totient is φ = 11919360.

The previous prime is 21168209. The next prime is 21168221. The reversal of 21168213 is 31286112.

It is not a de Polignac number, because 21168213 - 2² = 21168209 is a prime.

It is a super-2 number, since 2×21168213² = 896186483226738, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21168293) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54223 + ... + 54611.

It is an arithmetic number, because the mean of its divisors is an integer number (1031940).

Almost surely, 2^21168213 is an apocalyptic number.

It is an amenable number.

21168213 is a deficient number, since it is larger than the sum of its proper divisors (11853867).

21168213 is a wasteful number, since it uses less digits than its factorization.

21168213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 517.

The product of its digits is 576, while the sum is 24.

The square root of 21168213 is about 4600.8926307837. The cubic root of 21168213 is about 276.6271053576.

The spelling of 21168213 in words is "twenty-one million, one hundred sixty-eight thousand, two hundred thirteen".