1205521213 has 8 divisors (see below), whose sum is σ = 1343021400. Its totient is φ = 1074416448.

The previous prime is 1205521193. The next prime is 1205521279. The reversal of 1205521213 is 3121255021.

It can be written as a sum of positive squares in 4 ways, for example, as 210308004 + 995213209 = 14502^2 + 31547^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1205521213 - 2⁵ = 1205521181 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 (1205521613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1598458 + ... + 1599211.

It is an arithmetic number, because the mean of its divisors is an integer number (167877675).

Almost surely, 2^1205521213 is an apocalyptic number.

1205521213 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1205521213 is a deficient number, since it is larger than the sum of its proper divisors (137500187).

1205521213 is a wasteful number, since it uses less digits than its factorization.

1205521213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3197711.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 1205521213 is about 34720.6165411849. The cubic root of 1205521213 is about 1064.2858438886.

Adding to 1205521213 its reverse (3121255021), we get a palindrome (4326776234).

The spelling of 1205521213 in words is "one billion, two hundred five million, five hundred twenty-one thousand, two hundred thirteen".