1661356660 has 12 divisors (see below), whose sum is σ = 3488849028. Its totient is φ = 664542656.

The previous prime is 1661356657. The next prime is 1661356661. The reversal of 1661356660 is 666531661.

It can be written as a sum of positive squares in 2 ways, for example, as 1106094564 + 555262096 = 33258^2 + 23564^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661356661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41533897 + ... + 41533936.

It is an arithmetic number, because the mean of its divisors is an integer number (290737419).

Almost surely, 2^1661356660 is an apocalyptic number.

1661356660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661356660 is an abundant number, since it is smaller than the sum of its proper divisors (1827492368).

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

1661356660 is a wasteful number, since it uses less digits than its factorization.

1661356660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83067842 (or 83067840 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 1661356660 is about 40759.7431297107. The cubic root of 1661356660 is about 1184.3706201039.

The spelling of 1661356660 in words is "one billion, six hundred sixty-one million, three hundred fifty-six thousand, six hundred sixty".