921409 has 2 divisors, whose sum is σ = 921410. Its totient is φ = 921408.

The previous prime is 921407. The next prime is 921457. The reversal of 921409 is 904129.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 485809 + 435600 = 697^2 + 660^2 .

It is a cyclic number.

It is not a de Polignac number, because 921409 - 2¹ = 921407 is a prime.

Together with 921407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (921407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 460704 + 460705.

It is an arithmetic number, because the mean of its divisors is an integer number (460705).

2⁹²¹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

921409 is a deficient number, since it is larger than the sum of its proper divisors (1).

921409 is an equidigital number, since it uses as much as digits as its factorization.

921409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 921409 is about 959.9005156786. The cubic root of 921409 is about 97.3085086604.

The spelling of 921409 in words is "nine hundred twenty-one thousand, four hundred nine".