213121243 has 4 divisors (see below), whose sum is σ = 222387408. Its totient is φ = 203855080.

The previous prime is 213121241. The next prime is 213121273. The reversal of 213121243 is 342121312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 213121243 - 2¹ = 213121241 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 213121243.

It is not an unprimeable number, because it can be changed into a prime (213121241) 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, 4633048 + ... + 4633093.

It is an arithmetic number, because the mean of its divisors is an integer number (55596852).

Almost surely, 2^213121243 is an apocalyptic number.

213121243 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

213121243 is a deficient number, since it is larger than the sum of its proper divisors (9266165).

213121243 is an equidigital number, since it uses as much as digits as its factorization.

213121243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9266164.

The product of its digits is 288, while the sum is 19.

The square root of 213121243 is about 14598.6726451414. The cubic root of 213121243 is about 597.3225541711.

Adding to 213121243 its reverse (342121312), we get a palindrome (555242555).

The spelling of 213121243 in words is "two hundred thirteen million, one hundred twenty-one thousand, two hundred forty-three".