1661433661 has 8 divisors (see below), whose sum is σ = 1676401920. Its totient is φ = 1646506848.

The previous prime is 1661433643. The next prime is 1661433667. The reversal of 1661433661 is 1663341661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661433661 - 2⁵ = 1661433629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661433661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661433667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73170 + ... + 93148.

It is an arithmetic number, because the mean of its divisors is an integer number (209550240).

Almost surely, 2^1661433661 is an apocalyptic number.

It is an amenable number.

1661433661 is a deficient number, since it is larger than the sum of its proper divisors (14968259).

1661433661 is a wasteful number, since it uses less digits than its factorization.

1661433661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20723.

The product of its digits is 46656, while the sum is 37.

The square root of 1661433661 is about 40760.6876904696. The cubic root of 1661433661 is about 1184.3889176626.

The spelling of 1661433661 in words is "one billion, six hundred sixty-one million, four hundred thirty-three thousand, six hundred sixty-one".