20077978 has 4 divisors (see below), whose sum is σ = 30116970. Its totient is φ = 10038988.

The previous prime is 20077973. The next prime is 20077979. The reversal of 20077978 is 87977002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87977002 = 2 ⋅43988501.

It can be written as a sum of positive squares in only one way, i.e., 18896409 + 1181569 = 4347^2 + 1087^2 .

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 20077978.

It is not an unprimeable number, because it can be changed into a prime (20077973) 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 as a sum of consecutive naturals, namely, 5019493 + ... + 5019496.

Almost surely, 2^20077978 is an apocalyptic number.

20077978 is a deficient number, since it is larger than the sum of its proper divisors (10038992).

20077978 is a wasteful number, since it uses less digits than its factorization.

20077978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10038991.

The product of its (nonzero) digits is 49392, while the sum is 40.

The square root of 20077978 is about 4480.8456791101. The cubic root of 20077978 is about 271.7940789337.

The spelling of 20077978 in words is "twenty million, seventy-seven thousand, nine hundred seventy-eight".