1378421909 has 2 divisors, whose sum is σ = 1378421910. Its totient is φ = 1378421908.

The previous prime is 1378421879. The next prime is 1378421921. The reversal of 1378421909 is 9091248731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 914881009 + 463540900 = 30247^2 + 21530^2 .

It is a cyclic number.

It is not a de Polignac number, because 1378421909 - 2¹⁶ = 1378356373 is a prime.

It is a super-2 number, since 2×1378421909² = 3800093918422408562, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1378421909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1378423909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689210954 + 689210955.

It is an arithmetic number, because the mean of its divisors is an integer number (689210955).

Almost surely, 2^1378421909 is an apocalyptic number.

It is an amenable number.

1378421909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378421909 is an equidigital number, since it uses as much as digits as its factorization.

1378421909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 1378421909 is about 37127.1047753525. The cubic root of 1378421909 is about 1112.9117365676.

The spelling of 1378421909 in words is "one billion, three hundred seventy-eight million, four hundred twenty-one thousand, nine hundred nine".