1645813 has 4 divisors (see below), whose sum is σ = 1772428. Its totient is φ = 1519200.

The previous prime is 1645801. The next prime is 1645829. The reversal of 1645813 is 3185461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1034289 + 611524 = 1017^2 + 782^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645813 - 2¹⁷ = 1514741 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645843) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63288 + ... + 63313.

It is an arithmetic number, because the mean of its divisors is an integer number (443107).

2^1645813 is an apocalyptic number.

1645813 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1645813 is a deficient number, since it is larger than the sum of its proper divisors (126615).

1645813 is a wasteful number, since it uses less digits than its factorization.

1645813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126614.

The product of its digits is 2880, while the sum is 28.

The square root of 1645813 is about 1282.8924350857. The cubic root of 1645813 is about 118.0665381699.

It can be divided in two parts, 16458 and 13, that added together give a triangular number (16471 = T₁₈₁).

The spelling of 1645813 in words is "one million, six hundred forty-five thousand, eight hundred thirteen".