39661 has 4 divisors (see below), whose sum is σ = 42012. Its totient is φ = 37312.

The previous prime is 39659. The next prime is 39667. The reversal of 39661 is 16693.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 22500 + 17161 = 150^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 39661 - 2¹ = 39659 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39667) 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, 1150 + ... + 1183.

It is an arithmetic number, because the mean of its divisors is an integer number (10503).

2³⁹⁶⁶¹ is an apocalyptic number.

It is an amenable number.

39661 is a deficient number, since it is larger than the sum of its proper divisors (2351).

39661 is a wasteful number, since it uses less digits than its factorization.

39661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2350.

The product of its digits is 972, while the sum is 25.

The square root of 39661 is about 199.1506967098. The cubic root of 39661 is about 34.1026310666.

The spelling of 39661 in words is "thirty-nine thousand, six hundred sixty-one".