1601665720 has 64 divisors (see below), whose sum is σ = 3847979520. Its totient is φ = 598545024.

The previous prime is 1601665711. The next prime is 1601665733. The reversal of 1601665720 is 275661061.

It is a happy number.

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, 19317 + ... + 59803.

It is an arithmetic number, because the mean of its divisors is an integer number (60124680).

Almost surely, 2^1601665720 is an apocalyptic number.

1601665720 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 1601665720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1923989760).

1601665720 is an abundant number, since it is smaller than the sum of its proper divisors (2246313800).

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

1601665720 is a wasteful number, since it uses less digits than its factorization.

1601665720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40564 (or 40560 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 1601665720 is about 40020.8160836333. The cubic root of 1601665720 is about 1170.0128374173.

The spelling of 1601665720 in words is "one billion, six hundred one million, six hundred sixty-five thousand, seven hundred twenty".