1377921865 has 16 divisors (see below), whose sum is σ = 1674565200. Its totient is φ = 1088370432.

The previous prime is 1377921851. The next prime is 1377921869. The reversal of 1377921865 is 5681297731.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 258952464 + 1118969401 = 16092^2 + 33451^2 .

It is a cyclic number.

It is not a de Polignac number, because 1377921865 - 2¹⁹ = 1377397577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1377921869) 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 15 ways as a sum of consecutive naturals, for example, 155371 + ... + 163999.

It is an arithmetic number, because the mean of its divisors is an integer number (104660325).

Almost surely, 2^1377921865 is an apocalyptic number.

It is an amenable number.

1377921865 is a deficient number, since it is larger than the sum of its proper divisors (296643335).

1377921865 is a wasteful number, since it uses less digits than its factorization.

1377921865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9036.

The product of its digits is 635040, while the sum is 49.

The square root of 1377921865 is about 37120.3699469712. The cubic root of 1377921865 is about 1112.7771449403. Note that the first 3 decimals are identical.

The spelling of 1377921865 in words is "one billion, three hundred seventy-seven million, nine hundred twenty-one thousand, eight hundred sixty-five".