1966551 has 4 divisors (see below), whose sum is σ = 2622072. Its totient is φ = 1311032.

The previous prime is 1966511. The next prime is 1966561. The reversal of 1966551 is 1556691.

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 1966551 - 2¹⁰ = 1965527 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1966511) 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, 327756 + ... + 327761.

It is an arithmetic number, because the mean of its divisors is an integer number (655518).

2^1966551 is an apocalyptic number.

1966551 is a deficient number, since it is larger than the sum of its proper divisors (655521).

1966551 is an equidigital number, since it uses as much as digits as its factorization.

1966551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 655520.

The product of its digits is 8100, while the sum is 33.

The square root of 1966551 is about 1402.3376911429. The cubic root of 1966551 is about 125.2857675308.

The spelling of 1966551 in words is "one million, nine hundred sixty-six thousand, five hundred fifty-one".