661906005 has 16 divisors (see below), whose sum is σ = 1095569280. Its totient is φ = 340843328.

The previous prime is 661906001. The next prime is 661906019. The reversal of 661906005 is 500609166.

It is a cyclic number.

It is not a de Polignac number, because 661906005 - 2² = 661906001 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661906001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 760377 + ... + 761246.

It is an arithmetic number, because the mean of its divisors is an integer number (68473080).

Almost surely, 2^661906005 is an apocalyptic number.

It is an amenable number.

661906005 is a deficient number, since it is larger than the sum of its proper divisors (433663275).

661906005 is a wasteful number, since it uses less digits than its factorization.

661906005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521660.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 661906005 is about 25727.5339859847. The cubic root of 661906005 is about 871.4960848053.

The spelling of 661906005 in words is "six hundred sixty-one million, nine hundred six thousand, five".