1661433645 has 32 divisors (see below), whose sum is σ = 2699164800. Its totient is φ = 872515584.

The previous prime is 1661433643. The next prime is 1661433667. The reversal of 1661433645 is 5463341661.

It is not a de Polignac number, because 1661433645 - 2¹ = 1661433643 is a prime.

It is a super-3 number, since 3×1661433645³ (a number of 29 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661433643) 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 31 ways as a sum of consecutive naturals, for example, 1115061 + ... + 1116549.

It is an arithmetic number, because the mean of its divisors is an integer number (84348900).

Almost surely, 2^1661433645 is an apocalyptic number.

1661433645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661433645 is a deficient number, since it is larger than the sum of its proper divisors (1037731155).

1661433645 is a wasteful number, since it uses less digits than its factorization.

1661433645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2589.

The product of its digits is 155520, while the sum is 39.

The square root of 1661433645 is about 40760.6874942021. The cubic root of 1661433645 is about 1184.3889138606.

The spelling of 1661433645 in words is "one billion, six hundred sixty-one million, four hundred thirty-three thousand, six hundred forty-five".