213793821 has 18 divisors (see below), whose sum is σ = 310852542. Its totient is φ = 141593520.

The previous prime is 213793817. The next prime is 213793823. The reversal of 213793821 is 128397312.

It can be written as a sum of positive squares in only one way, i.e., 167417721 + 46376100 = 12939^2 + 6810^2 .

It is not a de Polignac number, because 213793821 - 2² = 213793817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213793823) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 463531 + ... + 463991.

Almost surely, 2^213793821 is an apocalyptic number.

It is an amenable number.

213793821 is a deficient number, since it is larger than the sum of its proper divisors (97058721).

213793821 is an equidigital number, since it uses as much as digits as its factorization.

213793821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921 (or 691 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 213793821 is about 14621.6900869906. The cubic root of 213793821 is about 597.9502471629.

It can be divided in two parts, 21379 and 3821, that added together give a triangular number (25200 = T₂₂₄).

The spelling of 213793821 in words is "two hundred thirteen million, seven hundred ninety-three thousand, eight hundred twenty-one".