1387781 has 2 divisors, whose sum is σ = 1387782. Its totient is φ = 1387780.

The previous prime is 1387733. The next prime is 1387783. The reversal of 1387781 is 1877831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 801025 + 586756 = 895^2 + 766^2 .

It is a cyclic number.

It is not a de Polignac number, because 1387781 - 2⁶ = 1387717 is a prime.

It is a super-2 number, since 2×1387781² = 3851872207922, which contains 22 as substring.

Together with 1387783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1387783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 693890 + 693891.

It is an arithmetic number, because the mean of its divisors is an integer number (693891).

2^1387781 is an apocalyptic number.

It is an amenable number.

1387781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1387781 is an equidigital number, since it uses as much as digits as its factorization.

1387781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9408, while the sum is 35.

The square root of 1387781 is about 1178.0411707576. The cubic root of 1387781 is about 111.5424841624.

The spelling of 1387781 in words is "one million, three hundred eighty-seven thousand, seven hundred eighty-one".