1978457 has 4 divisors (see below), whose sum is σ = 2130660. Its totient is φ = 1826256.

The previous prime is 1978441. The next prime is 1978463. The reversal of 1978457 is 7548791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7548791 = 71 ⋅106321.

It can be written as a sum of positive squares in 2 ways, for example, as 583696 + 1394761 = 764^2 + 1181^2 .

It is a cyclic number.

It is not a de Polignac number, because 1978457 - 2⁴ = 1978441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978157) 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, 76082 + ... + 76107.

It is an arithmetic number, because the mean of its divisors is an integer number (532665).

2^1978457 is an apocalyptic number.

It is an amenable number.

1978457 is a deficient number, since it is larger than the sum of its proper divisors (152203).

1978457 is a wasteful number, since it uses less digits than its factorization.

1978457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152202.

The product of its digits is 70560, while the sum is 41.

The square root of 1978457 is about 1406.5763399119. The cubic root of 1978457 is about 125.5380962952.

The spelling of 1978457 in words is "one million, nine hundred seventy-eight thousand, four hundred fifty-seven".