1661500603 has 4 divisors (see below), whose sum is σ = 1898857840. Its totient is φ = 1424143368.

The previous prime is 1661500591. The next prime is 1661500609. The reversal of 1661500603 is 3060051661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3060051661 = 3797 ⋅805913.

It is a cyclic number.

It is not a de Polignac number, because 1661500603 - 2¹⁷ = 1661369531 is a prime.

It is a Duffinian 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 3 ways as a sum of consecutive naturals, for example, 118678608 + ... + 118678621.

It is an arithmetic number, because the mean of its divisors is an integer number (474714460).

Almost surely, 2^1661500603 is an apocalyptic number.

1661500603 is a deficient number, since it is larger than the sum of its proper divisors (237357237).

1661500603 is an equidigital number, since it uses as much as digits as its factorization.

1661500603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 237357236.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 1661500603 is about 40761.5088410623. The cubic root of 1661500603 is about 1184.4048244665.

The spelling of 1661500603 in words is "one billion, six hundred sixty-one million, five hundred thousand, six hundred three".