1661425105 has 4 divisors (see below), whose sum is σ = 1993710132. Its totient is φ = 1329140080.

The previous prime is 1661425081. The next prime is 1661425121. The reversal of 1661425105 is 5015241661.

1661425105 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5015241661 = 43 ⋅116633527.

It can be written as a sum of positive squares in 2 ways, for example, as 308950929 + 1352474176 = 17577^2 + 36776^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1661425105 is a prime.

It is a super-3 number, since 3×1661425105³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166142506 + ... + 166142515.

It is an arithmetic number, because the mean of its divisors is an integer number (498427533).

Almost surely, 2^1661425105 is an apocalyptic number.

It is an amenable number.

1661425105 is a deficient number, since it is larger than the sum of its proper divisors (332285027).

1661425105 is an equidigital number, since it uses as much as digits as its factorization.

1661425105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332285026.

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 1661425105 is about 40760.5827362662. The cubic root of 1661425105 is about 1184.3868845492.

Adding to 1661425105 its reverse (5015241661), we get a palindrome (6676666766).

The spelling of 1661425105 in words is "one billion, six hundred sixty-one million, four hundred twenty-five thousand, one hundred five".