1661504643 has 10 divisors (see below), whose sum is σ = 2482000884. Its totient is φ = 1107669708.

The previous prime is 1661504617. The next prime is 1661504651. The reversal of 1661504643 is 3464051661.

It is a happy number.

1661504643 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 5 + 0 + 4 + 643 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-1661504643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1661504598 and 1661504607.

It is not an unprimeable number, because it can be changed into a prime (1661504683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 10256121 + ... + 10256282.

Almost surely, 2^1661504643 is an apocalyptic number.

1661504643 is a deficient number, since it is larger than the sum of its proper divisors (820496241).

1661504643 is an equidigital number, since it uses as much as digits as its factorization.

1661504643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20512415 (or 20512406 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 1661504643 is about 40761.5583975883. The cubic root of 1661504643 is about 1184.4057844404.

The spelling of 1661504643 in words is "one billion, six hundred sixty-one million, five hundred four thousand, six hundred forty-three".