7681661 has 8 divisors (see below), whose sum is σ = 8429400. Its totient is φ = 6956352.

The previous prime is 7681657. The next prime is 7681691. The reversal of 7681661 is 1661867.

7681661 = 531² + 532² + ... + 556².

It can be written as a sum of positive squares in 4 ways, for example, as 337561 + 7344100 = 581^2 + 2710^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 7681661 - 2² = 7681657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7681631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4886 + ... + 6263.

It is an arithmetic number, because the mean of its divisors is an integer number (1053675).

Almost surely, 2^7681661 is an apocalyptic number.

It is an amenable number.

7681661 is a deficient number, since it is larger than the sum of its proper divisors (747739).

7681661 is a wasteful number, since it uses less digits than its factorization.

7681661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11215.

The product of its digits is 12096, while the sum is 35.

The square root of 7681661 is about 2771.5809567826. The cubic root of 7681661 is about 197.3111884568.

The spelling of 7681661 in words is "seven million, six hundred eighty-one thousand, six hundred sixty-one".