212121009 has 12 divisors (see below), whose sum is σ = 308170356. Its totient is φ = 140595552.

The previous prime is 212120983. The next prime is 212121023. The reversal of 212121009 is 900121212.

212121009 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 152399025 + 59721984 = 12345^2 + 7728^2 .

It is not a de Polignac number, because 212121009 - 2⁵ = 212120977 is a prime.

It is a super-3 number, since 3×212121009³ (a number of 26 digits) contains 333 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 212120982 and 212121000.

It is not an unprimeable number, because it can be changed into a prime (212121029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 66562 + ... + 69675.

It is an arithmetic number, because the mean of its divisors is an integer number (25680863).

Almost surely, 2^212121009 is an apocalyptic number.

It is an amenable number.

212121009 is a deficient number, since it is larger than the sum of its proper divisors (96049347).

212121009 is a wasteful number, since it uses less digits than its factorization.

212121009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136416 (or 136413 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 212121009 is about 14564.3746518689. The cubic root of 212121009 is about 596.3866245464.

The spelling of 212121009 in words is "two hundred twelve million, one hundred twenty-one thousand, nine".