1219780561 has 4 divisors (see below), whose sum is σ = 1222678324. Its totient is φ = 1216882800.

The previous prime is 1219780559. The next prime is 1219780577. The reversal of 1219780561 is 1650879121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1650879121 = 1129 ⋅1462249.

It can be written as a sum of positive squares in 2 ways, for example, as 88736400 + 1131044161 = 9420^2 + 33631^2 .

It is a cyclic number.

It is not a de Polignac number, because 1219780561 - 2¹ = 1219780559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1219780501) 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, 1448250 + ... + 1449091.

It is an arithmetic number, because the mean of its divisors is an integer number (305669581).

Almost surely, 2^1219780561 is an apocalyptic number.

It is an amenable number.

1219780561 is a deficient number, since it is larger than the sum of its proper divisors (2897763).

1219780561 is an equidigital number, since it uses as much as digits as its factorization.

1219780561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2897762.

The product of its (nonzero) digits is 30240, while the sum is 40.

The square root of 1219780561 is about 34925.3569917331. The cubic root of 1219780561 is about 1068.4656615272.

The spelling of 1219780561 in words is "one billion, two hundred nineteen million, seven hundred eighty thousand, five hundred sixty-one".