561777779 has 4 divisors (see below), whose sum is σ = 562762200. Its totient is φ = 560793360.

The previous prime is 561777751. The next prime is 561777787. The reversal of 561777779 is 977777165.

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

It is a cyclic number.

It is not a de Polignac number, because 561777779 - 2¹⁶ = 561712243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (561777719) 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, 491354 + ... + 492495.

It is an arithmetic number, because the mean of its divisors is an integer number (140690550).

Almost surely, 2^561777779 is an apocalyptic number.

561777779 is a deficient number, since it is larger than the sum of its proper divisors (984421).

561777779 is an equidigital number, since it uses as much as digits as its factorization.

561777779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 984420.

The product of its digits is 4537890, while the sum is 56.

The square root of 561777779 is about 23701.8518052915. The cubic root of 561777779 is about 825.1283688832.

The spelling of 561777779 in words is "five hundred sixty-one million, seven hundred seventy-seven thousand, seven hundred seventy-nine".