12405551 has 4 divisors (see below), whose sum is σ = 12639672. Its totient is φ = 12171432.

The previous prime is 12405541. The next prime is 12405557. The reversal of 12405551 is 15550421.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 12405551 - 2¹⁸ = 12143407 is a prime.

It is a super-2 number, since 2×12405551² = 307795391227202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12405557) 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, 116981 + ... + 117086.

It is an arithmetic number, because the mean of its divisors is an integer number (3159918).

Almost surely, 2^12405551 is an apocalyptic number.

12405551 is a deficient number, since it is larger than the sum of its proper divisors (234121).

12405551 is an equidigital number, since it uses as much as digits as its factorization.

12405551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234120.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 12405551 is about 3522.1514731766. The cubic root of 12405551 is about 231.4934386975.

Adding to 12405551 its reverse (15550421), we get a palindrome (27955972).

The spelling of 12405551 in words is "twelve million, four hundred five thousand, five hundred fifty-one".