213356821 has 2 divisors, whose sum is σ = 213356822. Its totient is φ = 213356820.

The previous prime is 213356807. The next prime is 213356831. The reversal of 213356821 is 128653312.

213356821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155002500 + 58354321 = 12450^2 + 7639^2 .

It is a cyclic number.

It is not a de Polignac number, because 213356821 - 2⁹ = 213356309 is a prime.

It is a super-2 number, since 2×213356821² = 91042266134452082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213356831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106678410 + 106678411.

It is an arithmetic number, because the mean of its divisors is an integer number (106678411).

Almost surely, 2^213356821 is an apocalyptic number.

It is an amenable number.

213356821 is a deficient number, since it is larger than the sum of its proper divisors (1).

213356821 is an equidigital number, since it uses as much as digits as its factorization.

213356821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 31.

The square root of 213356821 is about 14606.7388899781. The cubic root of 213356821 is about 597.5425607656.

The spelling of 213356821 in words is "two hundred thirteen million, three hundred fifty-six thousand, eight hundred twenty-one".