1661915216 has 40 divisors (see below), whose sum is σ = 3493021224. Its totient is φ = 761425920.

The previous prime is 1661915191. The next prime is 1661915219. The reversal of 1661915216 is 6125191661.

It can be written as a sum of positive squares in 4 ways, for example, as 15178816 + 1646736400 = 3896^2 + 40580^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1661915216.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661915219) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 665 + ... + 57656.

Almost surely, 2^1661915216 is an apocalyptic number.

1661915216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661915216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1746510612).

1661915216 is an abundant number, since it is smaller than the sum of its proper divisors (1831106008).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661915216 is a wasteful number, since it uses less digits than its factorization.

1661915216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58479 (or 58473 counting only the distinct ones).

The product of its digits is 19440, while the sum is 38.

The square root of 1661915216 is about 40766.5943635227. The cubic root of 1661915216 is about 1184.5033355744.

The spelling of 1661915216 in words is "one billion, six hundred sixty-one million, nine hundred fifteen thousand, two hundred sixteen".