663811 has 4 divisors (see below), whose sum is σ = 666072. Its totient is φ = 661552.

The previous prime is 663797. The next prime is 663821. The reversal of 663811 is 118366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 118366 = 2 ⋅59183.

It is a cyclic number.

It is not a de Polignac number, because 663811 - 2⁷ = 663683 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (663821) 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, 610 + ... + 1303.

It is an arithmetic number, because the mean of its divisors is an integer number (166518).

2⁶⁶³⁸¹¹ is an apocalyptic number.

663811 is the 436-th centered heptagonal number.

663811 is a deficient number, since it is larger than the sum of its proper divisors (2261).

663811 is a wasteful number, since it uses less digits than its factorization.

663811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2260.

The product of its digits is 864, while the sum is 25.

The square root of 663811 is about 814.7459726811. The cubic root of 663811 is about 87.2331352204.

The spelling of 663811 in words is "six hundred sixty-three thousand, eight hundred eleven".