1661563216 has 20 divisors (see below), whose sum is σ = 3220186752. Its totient is φ = 830547296.

The previous prime is 1661563213. The next prime is 1661563247. The reversal of 1661563216 is 6123651661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661563213) 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, 53451 + ... + 78613.

Almost surely, 2^1661563216 is an apocalyptic number.

1661563216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1661563216 is a deficient number, since it is larger than the sum of its proper divisors (1558623536).

1661563216 is a wasteful number, since it uses less digits than its factorization.

1661563216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29298 (or 29292 counting only the distinct ones).

The product of its digits is 38880, while the sum is 37.

The square root of 1661563216 is about 40762.2768745810. The cubic root of 1661563216 is about 1184.4197022237.

The spelling of 1661563216 in words is "one billion, six hundred sixty-one million, five hundred sixty-three thousand, two hundred sixteen".