781409 has 2 divisors, whose sum is σ = 781410. Its totient is φ = 781408.

The previous prime is 781399. The next prime is 781423. The reversal of 781409 is 904187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 760384 + 21025 = 872^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 781409 - 2¹² = 777313 is a prime.

It is a super-2 number, since 2×781409² = 1221200050562, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (781309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390704 + 390705.

It is an arithmetic number, because the mean of its divisors is an integer number (390705).

2⁷⁸¹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

781409 is a deficient number, since it is larger than the sum of its proper divisors (1).

781409 is an equidigital number, since it uses as much as digits as its factorization.

781409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 781409 is about 883.9734158899. The cubic root of 781409 is about 92.1070351596.

The spelling of 781409 in words is "seven hundred eighty-one thousand, four hundred nine".