1551409 has 4 divisors (see below), whose sum is σ = 1553904. Its totient is φ = 1548916.

The previous prime is 1551383. The next prime is 1551449. The reversal of 1551409 is 9041551.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1551409 - 2⁹ = 1550897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551449) 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, 534 + ... + 1840.

It is an arithmetic number, because the mean of its divisors is an integer number (388476).

2^1551409 is an apocalyptic number.

It is an amenable number.

1551409 is a deficient number, since it is larger than the sum of its proper divisors (2495).

1551409 is a wasteful number, since it uses less digits than its factorization.

1551409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2494.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 1551409 is about 1245.5556992764. Note that the first 3 decimals coincide. The cubic root of 1551409 is about 115.7645093745.

The spelling of 1551409 in words is "one million, five hundred fifty-one thousand, four hundred nine".