1645891 has 6 divisors (see below), whose sum is σ = 1782420. Its totient is φ = 1519128.

The previous prime is 1645879. The next prime is 1645901. The reversal of 1645891 is 1985461.

It is not a de Polignac number, because 1645891 - 2¹¹ = 1643843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4701 + ... + 5038.

It is an arithmetic number, because the mean of its divisors is an integer number (297070).

2^1645891 is an apocalyptic number.

1645891 is a deficient number, since it is larger than the sum of its proper divisors (136529).

1645891 is an equidigital number, since it uses as much as digits as its factorization.

1645891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9765 (or 9752 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 1645891 is about 1282.9228347800. The cubic root of 1645891 is about 118.0684033158.

The spelling of 1645891 in words is "one million, six hundred forty-five thousand, eight hundred ninety-one".