1966421 has 4 divisors (see below), whose sum is σ = 1969344. Its totient is φ = 1963500.

The previous prime is 1966417. The next prime is 1966427. The reversal of 1966421 is 1246691.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1246691 = 139 ⋅8969.

It is a cyclic number.

It is not a de Polignac number, because 1966421 - 2² = 1966417 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1966427) 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, 116 + ... + 1986.

It is an arithmetic number, because the mean of its divisors is an integer number (492336).

2^1966421 is an apocalyptic number.

It is an amenable number.

1966421 is a deficient number, since it is larger than the sum of its proper divisors (2923).

1966421 is a wasteful number, since it uses less digits than its factorization.

1966421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2922.

The product of its digits is 2592, while the sum is 29.

The square root of 1966421 is about 1402.2913392017. The cubic root of 1966421 is about 125.2830067738.

The spelling of 1966421 in words is "one million, nine hundred sixty-six thousand, four hundred twenty-one".