1378686931 has 2 divisors, whose sum is σ = 1378686932. Its totient is φ = 1378686930.

The previous prime is 1378686919. The next prime is 1378686983. The reversal of 1378686931 is 1396868731.

It is an a-pointer prime, because the next prime (1378686983) can be obtained adding 1378686931 to its sum of digits (52).

It is a weak prime.

It is an emirp because it is prime and its reverse (1396868731) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1378686931 - 2²¹ = 1376589779 is a prime.

It is a super-2 number, since 2×1378686931² = 3801555307420397522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1378686031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689343465 + 689343466.

It is an arithmetic number, because the mean of its divisors is an integer number (689343466).

Almost surely, 2^1378686931 is an apocalyptic number.

1378686931 is the 23484-th centered pentagonal number.

1378686931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378686931 is an equidigital number, since it uses as much as digits as its factorization.

1378686931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1306368, while the sum is 52.

The square root of 1378686931 is about 37130.6737213318. The cubic root of 1378686931 is about 1112.9830565778.

The spelling of 1378686931 in words is "one billion, three hundred seventy-eight million, six hundred eighty-six thousand, nine hundred thirty-one".