1661320015 has 16 divisors (see below), whose sum is σ = 2086995456. Its totient is φ = 1267156000.

The previous prime is 1661319997. The next prime is 1661320027. The reversal of 1661320015 is 5100231661.

1661320015 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1661320015 - 2⁷ = 1661319887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 12540 + ... + 58990.

It is an arithmetic number, because the mean of its divisors is an integer number (130437216).

Almost surely, 2^1661320015 is an apocalyptic number.

1661320015 is a deficient number, since it is larger than the sum of its proper divisors (425675441).

1661320015 is a wasteful number, since it uses less digits than its factorization.

1661320015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46790.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 1661320015 is about 40759.2936028092. The cubic root of 1661320015 is about 1184.3619120439.

Adding to 1661320015 its reverse (5100231661), we get a palindrome (6761551676).

The spelling of 1661320015 in words is "one billion, six hundred sixty-one million, three hundred twenty thousand, fifteen".