1966391 has 4 divisors (see below), whose sum is σ = 2247312. Its totient is φ = 1685472.

The previous prime is 1966387. The next prime is 1966397. The reversal of 1966391 is 1936691.

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 1966391 - 2² = 1966387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1966397) 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, 140450 + ... + 140463.

It is an arithmetic number, because the mean of its divisors is an integer number (561828).

2^1966391 is an apocalyptic number.

1966391 is a deficient number, since it is larger than the sum of its proper divisors (280921).

1966391 is an equidigital number, since it uses as much as digits as its factorization.

1966391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280920.

The product of its digits is 8748, while the sum is 35.

The square root of 1966391 is about 1402.2806423823. The cubic root of 1966391 is about 125.2823696587.

The spelling of 1966391 in words is "one million, nine hundred sixty-six thousand, three hundred ninety-one".