1978217 has 4 divisors (see below), whose sum is σ = 1981056. Its totient is φ = 1975380.

The previous prime is 1978201. The next prime is 1978219. The reversal of 1978217 is 7128791.

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: 7128791 = 31 ⋅229961.

It is a cyclic number.

It is not a de Polignac number, because 1978217 - 2⁴ = 1978201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 428 + ... + 2034.

It is an arithmetic number, because the mean of its divisors is an integer number (495264).

2^1978217 is an apocalyptic number.

It is an amenable number.

1978217 is a deficient number, since it is larger than the sum of its proper divisors (2839).

1978217 is a wasteful number, since it uses less digits than its factorization.

1978217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2838.

The product of its digits is 7056, while the sum is 35.

The square root of 1978217 is about 1406.4910237893. The cubic root of 1978217 is about 125.5330198878.

The spelling of 1978217 in words is "one million, nine hundred seventy-eight thousand, two hundred seventeen".