1878715561 has 4 divisors (see below), whose sum is σ = 1879689412. Its totient is φ = 1877741712.

The previous prime is 1878715549. The next prime is 1878715603. The reversal of 1878715561 is 1655178781.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1274490000 + 604225561 = 35700^2 + 24581^2 .

It is a cyclic number.

It is not a de Polignac number, because 1878715561 - 2⁵ = 1878715529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1878715261) 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, 484026 + ... + 487891.

It is an arithmetic number, because the mean of its divisors is an integer number (469922353).

Almost surely, 2^1878715561 is an apocalyptic number.

It is an amenable number.

1878715561 is a deficient number, since it is larger than the sum of its proper divisors (973851).

1878715561 is an equidigital number, since it uses as much as digits as its factorization.

1878715561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973850.

The product of its digits is 470400, while the sum is 49.

The square root of 1878715561 is about 43344.1525583325. The cubic root of 1878715561 is about 1233.9200207431.

The spelling of 1878715561 in words is "one billion, eight hundred seventy-eight million, seven hundred fifteen thousand, five hundred sixty-one".