1661116640 has 96 divisors (see below), whose sum is σ = 4045204800. Its totient is φ = 644198400.

The previous prime is 1661116637. The next prime is 1661116651. The reversal of 1661116640 is 466111661.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 1661116597 and 1661116606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1186661 + ... + 1188059.

It is an arithmetic number, because the mean of its divisors is an integer number (42137550).

Almost surely, 2^1661116640 is an apocalyptic number.

1661116640 is a gapful number since it is divisible by the number (10) 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 1661116640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2022602400).

1661116640 is an abundant number, since it is smaller than the sum of its proper divisors (2384088160).

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

1661116640 is a wasteful number, since it uses less digits than its factorization.

1661116640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1636 (or 1628 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 1661116640 is about 40756.7986966592. The cubic root of 1661116640 is about 1184.3135811120.

The spelling of 1661116640 in words is "one billion, six hundred sixty-one million, one hundred sixteen thousand, six hundred forty".