213243551 has 4 divisors (see below), whose sum is σ = 213626952. Its totient is φ = 212860152.

The previous prime is 213243533. The next prime is 213243553. The reversal of 213243551 is 155342312.

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 213243551 - 2²⁶ = 146134687 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 213243551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213243553) 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, 190865 + ... + 191978.

It is an arithmetic number, because the mean of its divisors is an integer number (53406738).

Almost surely, 2^213243551 is an apocalyptic number.

213243551 is a deficient number, since it is larger than the sum of its proper divisors (383401).

213243551 is an equidigital number, since it uses as much as digits as its factorization.

213243551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 383400.

The product of its digits is 3600, while the sum is 26.

The square root of 213243551 is about 14602.8610552864. The cubic root of 213243551 is about 597.4367979927.

Adding to 213243551 its reverse (155342312), we get a palindrome (368585863).

The spelling of 213243551 in words is "two hundred thirteen million, two hundred forty-three thousand, five hundred fifty-one".