1645081 has 4 divisors (see below), whose sum is σ = 1649700. Its totient is φ = 1640464.

The previous prime is 1645019. The next prime is 1645087. The reversal of 1645081 is 1805461.

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 1177225 + 467856 = 1085^2 + 684^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1645081 is a prime.

It is a super-2 number, since 2×1645081² = 5412582993122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645087) 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, 1726 + ... + 2503.

It is an arithmetic number, because the mean of its divisors is an integer number (412425).

2^1645081 is an apocalyptic number.

It is an amenable number.

1645081 is a deficient number, since it is larger than the sum of its proper divisors (4619).

1645081 is an equidigital number, since it uses as much as digits as its factorization.

1645081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4618.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 1645081 is about 1282.6071105370. The cubic root of 1645081 is about 118.0490316200.

The spelling of 1645081 in words is "one million, six hundred forty-five thousand, eighty-one".