1291641660 has 288 divisors, whose sum is σ = 4404153600. Its totient is φ = 313372800.

The previous prime is 1291641647. The next prime is 1291641667. The reversal of 1291641660 is 661461921.

1291641660 is a `hidden beast` number, since 1 + 2 + 9 + 1 + 641 + 6 + 6 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291641667) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 9859795 + ... + 9859925.

It is an arithmetic number, because the mean of its divisors is an integer number (15292200).

Almost surely, 2^1291641660 is an apocalyptic number.

1291641660 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 1291641660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2202076800).

1291641660 is an abundant number, since it is smaller than the sum of its proper divisors (3112511940).

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

1291641660 is a wasteful number, since it uses less digits than its factorization.

1291641660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 1291641660 is about 35939.4165228096. The cubic root of 1291641660 is about 1089.0488180955.

The spelling of 1291641660 in words is "one billion, two hundred ninety-one million, six hundred forty-one thousand, six hundred sixty".