1661522720 has 192 divisors, whose sum is σ = 4663733760. Its totient is φ = 551424000.

The previous prime is 1661522719. The next prime is 1661522741. The reversal of 1661522720 is 272251661.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2310521 + ... + 2311239.

It is an arithmetic number, because the mean of its divisors is an integer number (24290280).

Almost surely, 2^1661522720 is an apocalyptic number.

1661522720 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 1661522720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2331866880).

1661522720 is an abundant number, since it is smaller than the sum of its proper divisors (3002211040).

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

1661522720 is a wasteful number, since it uses less digits than its factorization.

1661522720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 859 (or 851 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 1661522720 is about 40761.7801377712. The cubic root of 1661522720 is about 1184.4100798292.

The spelling of 1661522720 in words is "one billion, six hundred sixty-one million, five hundred twenty-two thousand, seven hundred twenty".