61665021 has 12 divisors (see below), whose sum is σ = 97169280. Its totient is φ = 37372680.

The previous prime is 61665017. The next prime is 61665029. The reversal of 61665021 is 12056616.

It is a happy number.

61665021 is a `hidden beast` number, since 6 + 1 + 6 + 650 + 2 + 1 = 666.

It is not a de Polignac number, because 61665021 - 2² = 61665017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61665029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 311341 + ... + 311538.

It is an arithmetic number, because the mean of its divisors is an integer number (8097440).

Almost surely, 2^61665021 is an apocalyptic number.

It is an amenable number.

61665021 is a deficient number, since it is larger than the sum of its proper divisors (35504259).

61665021 is a wasteful number, since it uses less digits than its factorization.

61665021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622896 (or 622893 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 61665021 is about 7852.7078769046. The cubic root of 61665021 is about 395.0750719888.

The spelling of 61665021 in words is "sixty-one million, six hundred sixty-five thousand, twenty-one".