6661961 has 4 divisors (see below), whose sum is σ = 6842052. Its totient is φ = 6481872.

The previous prime is 6661957. The next prime is 6661987. The reversal of 6661961 is 1691666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1691666 = 2 ⋅845833.

It can be written as a sum of positive squares in 2 ways, for example, as 5929225 + 732736 = 2435^2 + 856^2 .

It is a cyclic number.

It is not a de Polignac number, because 6661961 - 2² = 6661957 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6661901) 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, 89990 + ... + 90063.

It is an arithmetic number, because the mean of its divisors is an integer number (1710513).

Almost surely, 2^6661961 is an apocalyptic number.

It is an amenable number.

6661961 is a deficient number, since it is larger than the sum of its proper divisors (180091).

6661961 is a wasteful number, since it uses less digits than its factorization.

6661961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180090.

The product of its digits is 11664, while the sum is 35.

The square root of 6661961 is about 2581.0774881820. The cubic root of 6661961 is about 188.1629133346.

The spelling of 6661961 in words is "six million, six hundred sixty-one thousand, nine hundred sixty-one".