12355821 has 28 divisors (see below), whose sum is σ = 19634652. Its totient is φ = 7744896.

The previous prime is 12355813. The next prime is 12355823. The reversal of 12355821 is 12855321.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10150596 + 2205225 = 3186^2 + 1485^2 .

It is not a de Polignac number, because 12355821 - 2³ = 12355813 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12355823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 11895 + ... + 12891.

Almost surely, 2^12355821 is an apocalyptic number.

It is an amenable number.

12355821 is a deficient number, since it is larger than the sum of its proper divisors (7278831).

12355821 is an frugal number, since it uses more digits than its factorization.

12355821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1032 (or 1017 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 12355821 is about 3515.0847784940. The cubic root of 12355821 is about 231.1836960143.

Subtracting 12355821 from its reverse (12855321), we obtain a triangular number (499500 = T₉₉₉).

It can be divided in two parts, 1235 and 5821, that added together give a square (7056 = 84²).

The spelling of 12355821 in words is "twelve million, three hundred fifty-five thousand, eight hundred twenty-one".