21212182121 has 8 divisors (see below), whose sum is σ = 22853613384. Its totient is φ = 19572140160.

The previous prime is 21212182099. The next prime is 21212182163. The reversal of 21212182121 is 12128121212.

It can be written as a sum of positive squares in 4 ways, for example, as 1271635600 + 19940546521 = 35660^2 + 141211^2 .

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 21212182121 - 2¹⁰ = 21212181097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212188121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 315500 + ... + 376781.

It is an arithmetic number, because the mean of its divisors is an integer number (2856701673).

Almost surely, 2^21212182121 is an apocalyptic number.

It is an amenable number.

21212182121 is a deficient number, since it is larger than the sum of its proper divisors (1641431263).

21212182121 is a wasteful number, since it uses less digits than its factorization.

21212182121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694651.

The product of its digits is 256, while the sum is 23.

The spelling of 21212182121 in words is "twenty-one billion, two hundred twelve million, one hundred eighty-two thousand, one hundred twenty-one".