1661562720 has 480 divisors, whose sum is σ = 6224027040. Its totient is φ = 416931840.

The previous prime is 1661562703. The next prime is 1661562733. The reversal of 1661562720 is 272651661.

It is a happy number.

1661562720 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 5 + 627 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 28162051 + ... + 28162109.

It is an arithmetic number, because the mean of its divisors is an integer number (12966723).

Almost surely, 2^1661562720 is an apocalyptic number.

1661562720 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 1661562720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3112013520).

1661562720 is an abundant number, since it is smaller than the sum of its proper divisors (4562464320).

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

1661562720 is a wasteful number, since it uses less digits than its factorization.

1661562720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The square root of 1661562720 is about 40762.2707905239. The cubic root of 1661562720 is about 1184.4195843683.

The spelling of 1661562720 in words is "one billion, six hundred sixty-one million, five hundred sixty-two thousand, seven hundred twenty".