1378680991 has 4 divisors (see below), whose sum is σ = 1381752000. Its totient is φ = 1375609984.

The previous prime is 1378680959. The next prime is 1378681049. The reversal of 1378680991 is 1990868731.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1378680991 - 2⁵ = 1378680959 is a prime.

It is a super-2 number, since 2×1378680991² = 3801522549889484162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1378680931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1534831 + ... + 1535728.

It is an arithmetic number, because the mean of its divisors is an integer number (345438000).

Almost surely, 2^1378680991 is an apocalyptic number.

1378680991 is a deficient number, since it is larger than the sum of its proper divisors (3071009).

1378680991 is an equidigital number, since it uses as much as digits as its factorization.

1378680991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3071008.

The product of its (nonzero) digits is 653184, while the sum is 52.

The square root of 1378680991 is about 37130.5937334700. The cubic root of 1378680991 is about 1112.9814581659.

The spelling of 1378680991 in words is "one billion, three hundred seventy-eight million, six hundred eighty thousand, nine hundred ninety-one".