5645991 has 16 divisors (see below), whose sum is σ = 8225280. Its totient is φ = 3423840.

The previous prime is 5645957. The next prime is 5646019. The reversal of 5645991 is 1995465.

5645991 = T₂₀₈ + T₂₀₉ + ... + T₃₄₉.

It is not a de Polignac number, because 5645991 - 2¹⁰ = 5644967 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5645911) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1750 + ... + 3788.

It is an arithmetic number, because the mean of its divisors is an integer number (514080).

Almost surely, 2^5645991 is an apocalyptic number.

5645991 is a deficient number, since it is larger than the sum of its proper divisors (2579289).

5645991 is a wasteful number, since it uses less digits than its factorization.

5645991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2126.

The product of its digits is 48600, while the sum is 39.

The square root of 5645991 is about 2376.1294156674. The cubic root of 5645991 is about 178.0656135670.

It can be divided in two parts, 564 and 5991, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 5645991 in words is "five million, six hundred forty-five thousand, nine hundred ninety-one".