1551866 has 4 divisors (see below), whose sum is σ = 2327802. Its totient is φ = 775932.

The previous prime is 1551859. The next prime is 1551871. The reversal of 1551866 is 6681551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6681551 = 53 ⋅126067.

It can be written as a sum of positive squares in only one way, i.e., 1371241 + 180625 = 1171^2 + 425^2 .

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 387965 + ... + 387968.

2^1551866 is an apocalyptic number.

1551866 is a deficient number, since it is larger than the sum of its proper divisors (775936).

1551866 is an equidigital number, since it uses as much as digits as its factorization.

1551866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775935.

The product of its digits is 7200, while the sum is 32.

The square root of 1551866 is about 1245.7391380221. The cubic root of 1551866 is about 115.7758752118.

The spelling of 1551866 in words is "one million, five hundred fifty-one thousand, eight hundred sixty-six".