61664661 has 12 divisors (see below), whose sum is σ = 94310892. Its totient is φ = 38691456.

The previous prime is 61664653. The next prime is 61664663. The reversal of 61664661 is 16646616.

61664661 is a `hidden beast` number, since 6 + 1 + 6 + 646 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 53144100 + 8520561 = 7290^2 + 2919^2 .

It is not a de Polignac number, because 61664661 - 2³ = 61664653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61664663) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 201366 + ... + 201671.

It is an arithmetic number, because the mean of its divisors is an integer number (7859241).

Almost surely, 2^61664661 is an apocalyptic number.

It is an amenable number.

61664661 is a deficient number, since it is larger than the sum of its proper divisors (32646231).

61664661 is a wasteful number, since it uses less digits than its factorization.

61664661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403060 (or 403057 counting only the distinct ones).

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

The square root of 61664661 is about 7852.6849548419. The cubic root of 61664661 is about 395.0743031720.

The spelling of 61664661 in words is "sixty-one million, six hundred sixty-four thousand, six hundred sixty-one".