891409 has 2 divisors, whose sum is σ = 891410. Its totient is φ = 891408.

The previous prime is 891391. The next prime is 891421. The reversal of 891409 is 904198.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 497025 + 394384 = 705^2 + 628^2 .

It is a cyclic number.

It is not a de Polignac number, because 891409 - 2⁵ = 891377 is a prime.

It is a super-2 number, since 2×891409² = 1589220010562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (891439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445704 + 445705.

It is an arithmetic number, because the mean of its divisors is an integer number (445705).

2⁸⁹¹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

891409 is a deficient number, since it is larger than the sum of its proper divisors (1).

891409 is an equidigital number, since it uses as much as digits as its factorization.

891409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 891409 is about 944.1445863849. The cubic root of 891409 is about 96.2407513461.

The spelling of 891409 in words is "eight hundred ninety-one thousand, four hundred nine".