1661271505 has 8 divisors (see below), whose sum is σ = 1993842792. Its totient is φ = 1328805888.

The previous prime is 1661271481. The next prime is 1661271523. The reversal of 1661271505 is 5051721661.

It can be written as a sum of positive squares in 4 ways, for example, as 92794689 + 1568476816 = 9633^2 + 39604^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1661271505 - 2¹³ = 1661263313 is a prime.

It is a Duffinian 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, 13719 + ... + 59251.

It is an arithmetic number, because the mean of its divisors is an integer number (249230349).

Almost surely, 2^1661271505 is an apocalyptic number.

It is an amenable number.

1661271505 is a deficient number, since it is larger than the sum of its proper divisors (332571287).

1661271505 is an equidigital number, since it uses as much as digits as its factorization.

1661271505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52835.

The product of its (nonzero) digits is 12600, while the sum is 34.

The square root of 1661271505 is about 40758.6985194572. The cubic root of 1661271505 is about 1184.3503842718.

The spelling of 1661271505 in words is "one billion, six hundred sixty-one million, two hundred seventy-one thousand, five hundred five".