1921649 has 4 divisors (see below), whose sum is σ = 1926000. Its totient is φ = 1917300.

The previous prime is 1921631. The next prime is 1921657. The reversal of 1921649 is 9461291.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1921649 - 2⁸ = 1921393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1921849) 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 in 3 ways as a sum of consecutive naturals, for example, 1427 + ... + 2424.

It is an arithmetic number, because the mean of its divisors is an integer number (481500).

2^1921649 is an apocalyptic number.

It is an amenable number.

1921649 is a deficient number, since it is larger than the sum of its proper divisors (4351).

1921649 is an equidigital number, since it uses as much as digits as its factorization.

1921649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4350.

The product of its digits is 3888, while the sum is 32.

The square root of 1921649 is about 1386.2355499698. The cubic root of 1921649 is about 124.3248721842.

The spelling of 1921649 in words is "one million, nine hundred twenty-one thousand, six hundred forty-nine".