1661003640 has 96 divisors (see below), whose sum is σ = 5404744800. Its totient is φ = 442402560.

The previous prime is 1661003629. The next prime is 1661003711. The reversal of 1661003640 is 463001661.

1661003640 is a `hidden beast` number, since 1 + 6 + 6 + 10 + 0 + 3 + 640 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 365301 + ... + 369819.

It is an arithmetic number, because the mean of its divisors is an integer number (56299425).

Almost surely, 2^1661003640 is an apocalyptic number.

1661003640 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 1661003640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2702372400).

1661003640 is an abundant number, since it is smaller than the sum of its proper divisors (3743741160).

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

1661003640 is a wasteful number, since it uses less digits than its factorization.

1661003640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5557 (or 5550 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 1661003640 is about 40755.4124012995. The cubic root of 1661003640 is about 1184.2867255888.

The spelling of 1661003640 in words is "one billion, six hundred sixty-one million, three thousand, six hundred forty".