20394778 has 4 divisors (see below), whose sum is σ = 30592170. Its totient is φ = 10197388.

The previous prime is 20394769. The next prime is 20394793. The reversal of 20394778 is 87749302.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18722929 + 1671849 = 4327^2 + 1293^2 .

It is a super-3 number, since 3×20394778³ (a number of 23 digits) contains 333 as substring.

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 20394778.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5098693 + ... + 5098696.

Almost surely, 2^20394778 is an apocalyptic number.

20394778 is a deficient number, since it is larger than the sum of its proper divisors (10197392).

20394778 is a wasteful number, since it uses less digits than its factorization.

20394778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10197391.

The product of its (nonzero) digits is 84672, while the sum is 40.

The square root of 20394778 is about 4516.0577941386. The cubic root of 20394778 is about 273.2161249733.

The spelling of 20394778 in words is "twenty million, three hundred ninety-four thousand, seven hundred seventy-eight".