6663861 has 6 divisors (see below), whose sum is σ = 9625590. Its totient is φ = 4442568.

The previous prime is 6663857. The next prime is 6663863. The reversal of 6663861 is 1683666.

It can be written as a sum of positive squares in only one way, i.e., 6200100 + 463761 = 2490^2 + 681^2 .

It is not a de Polignac number, because 6663861 - 2² = 6663857 is a prime.

It is a Curzon number.

6663861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6663863) 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, 370206 + ... + 370223.

It is an arithmetic number, because the mean of its divisors is an integer number (1604265).

Almost surely, 2^6663861 is an apocalyptic number.

It is an amenable number.

6663861 is a deficient number, since it is larger than the sum of its proper divisors (2961729).

6663861 is a wasteful number, since it uses less digits than its factorization.

6663861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740435 (or 740432 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 6663861 is about 2581.4455252823. The cubic root of 6663861 is about 188.1807997373.

The spelling of 6663861 in words is "six million, six hundred sixty-three thousand, eight hundred sixty-one".