1561676278 has 4 divisors (see below), whose sum is σ = 2342514420. Its totient is φ = 780838138.

The previous prime is 1561676239. The next prime is 1561676297. The reversal of 1561676278 is 8726761651.

It is a happy number.

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

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390419068 + ... + 390419071.

It is an arithmetic number, because the mean of its divisors is an integer number (585628605).

Almost surely, 2^1561676278 is an apocalyptic number.

1561676278 is a deficient number, since it is larger than the sum of its proper divisors (780838142).

1561676278 is an equidigital number, since it uses as much as digits as its factorization.

1561676278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780838141.

The product of its digits is 846720, while the sum is 49.

The square root of 1561676278 is about 39518.0500278038. The cubic root of 1561676278 is about 1160.1932590215.

The spelling of 1561676278 in words is "one billion, five hundred sixty-one million, six hundred seventy-six thousand, two hundred seventy-eight".