23212121 has 4 divisors (see below), whose sum is σ = 23417652. Its totient is φ = 23006592.

The previous prime is 23212099. The next prime is 23212139. The reversal of 23212121 is 12121232.

It is a happy number.

23212121 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8497225 + 14714896 = 2915^2 + 3836^2 .

It is a cyclic number.

It is not a de Polignac number, because 23212121 - 2¹⁸ = 22949977 is a prime.

It is a super-2 number, since 2×23212121² = 1077605122637282, which contains 22 as substring.

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

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 23212096 and 23212105.

It is not an unprimeable number, because it can be changed into a prime (23211121) 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, 102596 + ... + 102821.

It is an arithmetic number, because the mean of its divisors is an integer number (5854413).

Almost surely, 2^23212121 is an apocalyptic number.

It is an amenable number.

23212121 is a deficient number, since it is larger than the sum of its proper divisors (205531).

23212121 is a wasteful number, since it uses less digits than its factorization.

23212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205530.

The product of its digits is 48, while the sum is 14.

The square root of 23212121 is about 4817.8959100421. The cubic root of 23212121 is about 285.2582905194.

Adding to 23212121 its reverse (12121232), we get a palindrome (35333353).

It can be divided in two parts, 2 and 3212121, that added together give a palindrome (3212123).

The spelling of 23212121 in words is "twenty-three million, two hundred twelve thousand, one hundred twenty-one".