1661613556 has 12 divisors (see below), whose sum is σ = 2910645892. Its totient is φ = 830000448.

The previous prime is 1661613539. The next prime is 1661613559. The reversal of 1661613556 is 6553161661.

It can be written as a sum of positive squares in 2 ways, for example, as 1622800656 + 38812900 = 40284^2 + 6230^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661613559) 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, 196935 + ... + 205198.

Almost surely, 2^1661613556 is an apocalyptic number.

It is an amenable number.

1661613556 is a deficient number, since it is larger than the sum of its proper divisors (1249032336).

1661613556 is a wasteful number, since it uses less digits than its factorization.

1661613556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403170 (or 403168 counting only the distinct ones).

The product of its digits is 97200, while the sum is 40.

The square root of 1661613556 is about 40762.8943525849. The cubic root of 1661613556 is about 1184.4316634670.

The spelling of 1661613556 in words is "one billion, six hundred sixty-one million, six hundred thirteen thousand, five hundred fifty-six".