1381999 has 2 divisors, whose sum is σ = 1382000. Its totient is φ = 1381998.

The previous prime is 1381997. The next prime is 1382021. The reversal of 1381999 is 9991831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1381999 - 2¹ = 1381997 is a prime.

Together with 1381997, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1381993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 690999 + 691000.

It is an arithmetic number, because the mean of its divisors is an integer number (691000).

2^1381999 is an apocalyptic number.

1381999 is a deficient number, since it is larger than the sum of its proper divisors (1).

1381999 is an equidigital number, since it uses as much as digits as its factorization.

1381999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 40.

The square root of 1381999 is about 1175.5845354546. The cubic root of 1381999 is about 111.3873596854.

The spelling of 1381999 in words is "one million, three hundred eighty-one thousand, nine hundred ninety-nine".