213240421 has 4 divisors (see below), whose sum is σ = 213465132. Its totient is φ = 213015712.

The previous prime is 213240409. The next prime is 213240437. The reversal of 213240421 is 124042312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 132940900 + 80299521 = 11530^2 + 8961^2 .

It is a cyclic number.

It is not a de Polignac number, because 213240421 - 2²⁷ = 79022693 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 (213240481) 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, 110926 + ... + 112831.

It is an arithmetic number, because the mean of its divisors is an integer number (53366283).

Almost surely, 2^213240421 is an apocalyptic number.

It is an amenable number.

213240421 is a deficient number, since it is larger than the sum of its proper divisors (224711).

213240421 is an equidigital number, since it uses as much as digits as its factorization.

213240421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224710.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 213240421 is about 14602.7538841138. The cubic root of 213240421 is about 597.4338749089.

Adding to 213240421 its reverse (124042312), we get a palindrome (337282733).

The spelling of 213240421 in words is "two hundred thirteen million, two hundred forty thousand, four hundred twenty-one".