23856821 has 6 divisors (see below), whose sum is σ = 24706710. Its totient is φ = 23008776.

The previous prime is 23856817. The next prime is 23856829. The reversal of 23856821 is 12865832.

It can be written as a sum of positive squares in only one way, i.e., 20566225 + 3290596 = 4535^2 + 1814^2 .

It is not a de Polignac number, because 23856821 - 2² = 23856817 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 (23856829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25850 + ... + 26756.

It is an arithmetic number, because the mean of its divisors is an integer number (4117785).

Almost surely, 2^23856821 is an apocalyptic number.

It is an amenable number.

23856821 is a deficient number, since it is larger than the sum of its proper divisors (849889).

23856821 is an frugal number, since it uses more digits than its factorization.

23856821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1843 (or 936 counting only the distinct ones).

The product of its digits is 23040, while the sum is 35.

The square root of 23856821 is about 4884.3444800710. The cubic root of 23856821 is about 287.8751588873.

The spelling of 23856821 in words is "twenty-three million, eight hundred fifty-six thousand, eight hundred twenty-one".