1661500605 has 16 divisors (see below), whose sum is σ = 2723241024. Its totient is φ = 864520320.

The previous prime is 1661500591. The next prime is 1661500609. The reversal of 1661500605 is 5060051661.

It is not a de Polignac number, because 1661500605 - 2⁵ = 1661500573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661500609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1350199 + ... + 1351428.

It is an arithmetic number, because the mean of its divisors is an integer number (170202564).

Almost surely, 2^1661500605 is an apocalyptic number.

1661500605 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661500605 is a deficient number, since it is larger than the sum of its proper divisors (1061740419).

1661500605 is a wasteful number, since it uses less digits than its factorization.

1661500605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2701676.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 1661500605 is about 40761.5088655952. The cubic root of 1661500605 is about 1184.4048249417.

The spelling of 1661500605 in words is "one billion, six hundred sixty-one million, five hundred thousand, six hundred five".