1378186861 has 2 divisors, whose sum is σ = 1378186862. Its totient is φ = 1378186860.

The previous prime is 1378186829. The next prime is 1378186867. The reversal of 1378186861 is 1686818731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 956664900 + 421521961 = 30930^2 + 20531^2 .

It is a cyclic number.

It is not a de Polignac number, because 1378186861 - 2⁵ = 1378186829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1378186867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689093430 + 689093431.

It is an arithmetic number, because the mean of its divisors is an integer number (689093431).

Almost surely, 2^1378186861 is an apocalyptic number.

It is an amenable number.

1378186861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378186861 is an equidigital number, since it uses as much as digits as its factorization.

1378186861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 387072, while the sum is 49.

The square root of 1378186861 is about 37123.9391902314. The cubic root of 1378186861 is about 1112.8484752042.

The spelling of 1378186861 in words is "one billion, three hundred seventy-eight million, one hundred eighty-six thousand, eight hundred sixty-one".