1378209555 has 72 divisors (see below), whose sum is σ = 2581186608. Its totient is φ = 679819392.

The previous prime is 1378209493. The next prime is 1378209571. The reversal of 1378209555 is 5559028731.

1378209555 is a `hidden beast` number, since 1 + 3 + 78 + 20 + 9 + 555 = 666.

It is not a de Polignac number, because 1378209555 - 2¹¹ = 1378207507 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1378209555.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 697549 + ... + 699521.

It is an arithmetic number, because the mean of its divisors is an integer number (35849814).

Almost surely, 2^1378209555 is an apocalyptic number.

1378209555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1378209555 is a deficient number, since it is larger than the sum of its proper divisors (1202977053).

1378209555 is a wasteful number, since it uses less digits than its factorization.

1378209555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2065 (or 2043 counting only the distinct ones).

The product of its (nonzero) digits is 378000, while the sum is 45.

The square root of 1378209555 is about 37124.2448408045. The cubic root of 1378209555 is about 1112.8545834337.

The spelling of 1378209555 in words is "one billion, three hundred seventy-eight million, two hundred nine thousand, five hundred fifty-five".