1378778731 has 4 divisors (see below), whose sum is σ = 1504122264. Its totient is φ = 1253435200.

The previous prime is 1378778717. The next prime is 1378778759.

1378778731 is nontrivially palindromic in base 10.

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 1378778731 - 2¹⁹ = 1378254443 is a prime.

It is a super-2 number, since 2×1378778731² = 3802061578115940722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1378778431) 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, 62671750 + ... + 62671771.

It is an arithmetic number, because the mean of its divisors is an integer number (376030566).

Almost surely, 2^1378778731 is an apocalyptic number.

1378778731 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1378778731 is a deficient number, since it is larger than the sum of its proper divisors (125343533).

1378778731 is a wasteful number, since it uses less digits than its factorization.

1378778731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125343532.

The product of its digits is 1382976, while the sum is 52.

The square root of 1378778731 is about 37131.9098754696. The cubic root of 1378778731 is about 1113.0077587236.

The spelling of 1378778731 in words is "one billion, three hundred seventy-eight million, seven hundred seventy-eight thousand, seven hundred thirty-one".