23121821 has 2 divisors, whose sum is σ = 23121822. Its totient is φ = 23121820.

The previous prime is 23121817. The next prime is 23121851. The reversal of 23121821 is 12812132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21996100 + 1125721 = 4690^2 + 1061^2 .

It is a cyclic number.

It is not a de Polignac number, because 23121821 - 2² = 23121817 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 23121793 and 23121802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23121851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11560910 + 11560911.

It is an arithmetic number, because the mean of its divisors is an integer number (11560911).

Almost surely, 2^23121821 is an apocalyptic number.

It is an amenable number.

23121821 is a deficient number, since it is larger than the sum of its proper divisors (1).

23121821 is an equidigital number, since it uses as much as digits as its factorization.

23121821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 20.

The square root of 23121821 is about 4808.5154673766. The cubic root of 23121821 is about 284.8879050296.

Adding to 23121821 its reverse (12812132), we get a palindrome (35933953).

The spelling of 23121821 in words is "twenty-three million, one hundred twenty-one thousand, eight hundred twenty-one".