1366821 has 32 divisors (see below), whose sum is σ = 2211840. Its totient is φ = 831600.

The previous prime is 1366801. The next prime is 1366829. The reversal of 1366821 is 1286631.

It is not a de Polignac number, because 1366821 - 2⁷ = 1366693 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 (1366829) 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 31 ways as a sum of consecutive naturals, for example, 19216 + ... + 19286.

It is an arithmetic number, because the mean of its divisors is an integer number (69120).

2^1366821 is an apocalyptic number.

It is an amenable number.

1366821 is a deficient number, since it is larger than the sum of its proper divisors (845019).

1366821 is a wasteful number, since it uses less digits than its factorization.

1366821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134 (or 128 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 1366821 is about 1169.1112008701. Note that the first 3 decimals coincide. The cubic root of 1366821 is about 110.9780818666.

It can be divided in two parts, 13668 and 21, that added together give a square (13689 = 117²).

The spelling of 1366821 in words is "one million, three hundred sixty-six thousand, eight hundred twenty-one".