521212121 has 8 divisors (see below), whose sum is σ = 530841024. Its totient is φ = 511618320.

The previous prime is 521212103. The next prime is 521212127. The reversal of 521212121 is 121212125.

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 521212121 - 2⁶ = 521212057 is a prime.

It is an alternating number because its digits alternate between odd and even.

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 521212121.

It is not an unprimeable number, because it can be changed into a prime (521212127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22190 + ... + 39176.

It is an arithmetic number, because the mean of its divisors is an integer number (66355128).

Almost surely, 2^521212121 is an apocalyptic number.

It is an amenable number.

521212121 is a deficient number, since it is larger than the sum of its proper divisors (9628903).

521212121 is a wasteful number, since it uses less digits than its factorization.

521212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17551.

The product of its digits is 80, while the sum is 17.

The square root of 521212121 is about 22830.0705430360. The cubic root of 521212121 is about 804.7694881574.

Adding to 521212121 its reverse (121212125), we get a palindrome (642424246).

The spelling of 521212121 in words is "five hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".