1620778 has 4 divisors (see below), whose sum is σ = 2431170. Its totient is φ = 810388.

The previous prime is 1620769. The next prime is 1620803. The reversal of 1620778 is 8770261.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8770261 = 263 ⋅33347.

It can be written as a sum of positive squares in only one way, i.e., 1520289 + 100489 = 1233^2 + 317^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 405193 + ... + 405196.

2^1620778 is an apocalyptic number.

1620778 is a deficient number, since it is larger than the sum of its proper divisors (810392).

1620778 is an equidigital number, since it uses as much as digits as its factorization.

1620778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 810391.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 1620778 is about 1273.0977967148. The cubic root of 1620778 is about 117.4648272572.

The spelling of 1620778 in words is "one million, six hundred twenty thousand, seven hundred seventy-eight".