212123212421 has 4 divisors (see below), whose sum is σ = 212124187692. Its totient is φ = 212122237152.

The previous prime is 212123212369. The next prime is 212123212423. The reversal of 212123212421 is 124212321212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 92728776196 + 119394436225 = 304514^2 + 345535^2 .

It is a cyclic number.

It is not a de Polignac number, because 212123212421 - 2³⁴ = 194943343237 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 (212123212423) 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, 3515 + ... + 651351.

It is an arithmetic number, because the mean of its divisors is an integer number (53031046923).

Almost surely, 2^212123212421 is an apocalyptic number.

It is an amenable number.

212123212421 is a deficient number, since it is larger than the sum of its proper divisors (975271).

212123212421 is an equidigital number, since it uses as much as digits as its factorization.

212123212421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 975270.

The product of its digits is 768, while the sum is 23.

Adding to 212123212421 its reverse (124212321212), we get a palindrome (336335533633).

The spelling of 212123212421 in words is "two hundred twelve billion, one hundred twenty-three million, two hundred twelve thousand, four hundred twenty-one".