990778 has 4 divisors (see below), whose sum is σ = 1486170. Its totient is φ = 495388.

The previous prime is 990767. The next prime is 990797. The reversal of 990778 is 877099.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 877099 = 307 ⋅2857.

It can be written as a sum of positive squares in only one way, i.e., 727609 + 263169 = 853^2 + 513^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 990778.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 247693 + ... + 247696.

2⁹⁹⁰⁷⁷⁸ is an apocalyptic number.

990778 is a deficient number, since it is larger than the sum of its proper divisors (495392).

990778 is a wasteful number, since it uses less digits than its factorization.

990778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495391.

The product of its (nonzero) digits is 31752, while the sum is 40.

The square root of 990778 is about 995.3783200372. The cubic root of 990778 is about 99.6916501812.

The spelling of 990778 in words is "nine hundred ninety thousand, seven hundred seventy-eight".