1861975661 has 32 divisors (see below), whose sum is σ = 2490163200. Its totient is φ = 1350613440.

The previous prime is 1861975607. The next prime is 1861975673. The reversal of 1861975661 is 1665791681.

It is a cyclic number.

It is not a de Polignac number, because 1861975661 - 2¹⁴ = 1861959277 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 (1861975061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36230 + ... + 70968.

It is an arithmetic number, because the mean of its divisors is an integer number (77817600).

Almost surely, 2^1861975661 is an apocalyptic number.

It is an amenable number.

1861975661 is a deficient number, since it is larger than the sum of its proper divisors (628187539).

1861975661 is a wasteful number, since it uses less digits than its factorization.

1861975661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34809.

The product of its digits is 544320, while the sum is 50.

The square root of 1861975661 is about 43150.6159979206. The cubic root of 1861975661 is about 1230.2442199091.

The spelling of 1861975661 in words is "one billion, eight hundred sixty-one million, nine hundred seventy-five thousand, six hundred sixty-one".