1644491 has 2 divisors, whose sum is σ = 1644492. Its totient is φ = 1644490.

The previous prime is 1644451. The next prime is 1644493. The reversal of 1644491 is 1944461.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644491 is a prime.

It is a Sophie Germain prime.

Together with 1644493, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1644493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822245 + 822246.

It is an arithmetic number, because the mean of its divisors is an integer number (822246).

2^1644491 is an apocalyptic number.

1644491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644491 is an equidigital number, since it uses as much as digits as its factorization.

1644491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 29.

The square root of 1644491 is about 1282.3770896269. The cubic root of 1644491 is about 118.0349173694.

The spelling of 1644491 in words is "one million, six hundred forty-four thousand, four hundred ninety-one".