20780977 has 4 divisors (see below), whose sum is σ = 23749696. Its totient is φ = 17812260.

The previous prime is 20780957. The next prime is 20780999. The reversal of 20780977 is 77908702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20780977 - 2¹⁹ = 20256689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20780957) 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, 1484349 + ... + 1484362.

It is an arithmetic number, because the mean of its divisors is an integer number (5937424).

Almost surely, 2^20780977 is an apocalyptic number.

It is an amenable number.

20780977 is a deficient number, since it is larger than the sum of its proper divisors (2968719).

20780977 is an equidigital number, since it uses as much as digits as its factorization.

20780977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2968718.

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

The square root of 20780977 is about 4558.6156890003. The cubic root of 20780977 is about 274.9299083074.

The spelling of 20780977 in words is "twenty million, seven hundred eighty thousand, nine hundred seventy-seven".