1661809015 has 8 divisors (see below), whose sum is σ = 2009394288. Its totient is φ = 1319298240.

The previous prime is 1661808959. The next prime is 1661809021. The reversal of 1661809015 is 5109081661.

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

It is not a de Polignac number, because 1661809015 - 2⁷ = 1661808887 is a prime.

It is a super-3 number, since 3×1661809015³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

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, 1267902 + ... + 1269211.

It is an arithmetic number, because the mean of its divisors is an integer number (251174286).

Almost surely, 2^1661809015 is an apocalyptic number.

1661809015 is a deficient number, since it is larger than the sum of its proper divisors (347585273).

1661809015 is a wasteful number, since it uses less digits than its factorization.

1661809015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2537249.

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 1661809015 is about 40765.2917933872. The cubic root of 1661809015 is about 1184.4781040188.

The spelling of 1661809015 in words is "one billion, six hundred sixty-one million, eight hundred nine thousand, fifteen".