7661 has 4 divisors (see below), whose sum is σ = 7872.
Its totient is φ = 7452.
The previous prime is 7649. The next prime is 7669. The reversal of 7661 is 1667.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 7661 - 210 = 6637 is a prime.
It is a Duffinian number.
It is a nialpdrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (7669) 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, 35 + ... + 128.
It is an arithmetic number, because the mean of its divisors is an integer number (1968).
27661 is an apocalyptic number.
It is an amenable number.
7661 is a deficient number, since it is larger than the sum of its proper divisors (211).
7661 is a wasteful number, since it uses less digits than its factorization.
7661 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 210.
The product of its digits is 252, while the sum is 20.
The square root of 7661 is about 87.5271386485.
The cubic root of 7661 is about 19.7134130098.
It can be divided in two parts, 766 and 1, that added together give a palindrome (767).
The spelling of 7661 in words is "seven thousand, six hundred sixty-one".