1661128305 has 8 divisors (see below), whose sum is σ = 2657805312. Its totient is φ = 885935088.

The previous prime is 1661128297. The next prime is 1661128319. The reversal of 1661128305 is 5038211661.

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

It is not a de Polignac number, because 1661128305 - 2³ = 1661128297 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55370929 + ... + 55370958.

It is an arithmetic number, because the mean of its divisors is an integer number (332225664).

Almost surely, 2^1661128305 is an apocalyptic number.

1661128305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661128305 is a deficient number, since it is larger than the sum of its proper divisors (996677007).

1661128305 is a wasteful number, since it uses less digits than its factorization.

1661128305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110741895.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 1661128305 is about 40756.9418013668. The cubic root of 1661128305 is about 1184.3163533407.

Adding to 1661128305 its reverse (5038211661), we get a palindrome (6699339966).

The spelling of 1661128305 in words is "one billion, six hundred sixty-one million, one hundred twenty-eight thousand, three hundred five".