12723821 has 4 divisors (see below), whose sum is σ = 13880544. Its totient is φ = 11567100.

The previous prime is 12723797. The next prime is 12723833. The reversal of 12723821 is 12832721.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12723821 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 (12723121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 578345 + ... + 578366.

It is an arithmetic number, because the mean of its divisors is an integer number (3470136).

Almost surely, 2^12723821 is an apocalyptic number.

12723821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12723821 is a deficient number, since it is larger than the sum of its proper divisors (1156723).

12723821 is a wasteful number, since it uses less digits than its factorization.

12723821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1156722.

The product of its digits is 1344, while the sum is 26.

The square root of 12723821 is about 3567.0465374032. The cubic root of 12723821 is about 233.4564354958.

Subtracting 12723821 from its reverse (12832721), we obtain a square (108900 = 330²).

The spelling of 12723821 in words is "twelve million, seven hundred twenty-three thousand, eight hundred twenty-one".