1661201365 has 16 divisors (see below), whose sum is σ = 2004621696. Its totient is φ = 1321528000.

The previous prime is 1661201357. The next prime is 1661201401. The reversal of 1661201365 is 5631021661.

It is not a de Polignac number, because 1661201365 - 2³ = 1661201357 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, 1276215 + ... + 1277515.

It is an arithmetic number, because the mean of its divisors is an integer number (125288856).

Almost surely, 2^1661201365 is an apocalyptic number.

It is an amenable number.

1661201365 is a deficient number, since it is larger than the sum of its proper divisors (343420331).

1661201365 is a wasteful number, since it uses less digits than its factorization.

1661201365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2540.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 1661201365 is about 40757.8380805459. The cubic root of 1661201365 is about 1184.3337160140. Note that the first 3 decimals are identical.

The spelling of 1661201365 in words is "one billion, six hundred sixty-one million, two hundred one thousand, three hundred sixty-five".