660909101581 has 8 divisors (see below), whose sum is σ = 663278598584. Its totient is φ = 658543841280.

The previous prime is 660909101579. The next prime is 660909101603. The reversal of 660909101581 is 185101909066.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 105423596100 + 555485505481 = 324690^2 + 745309^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(660909101581) divides (660909101581-1)⁶.

It is a cyclic number.

It is not a de Polignac number, because 660909101581 - 2¹ = 660909101579 is a prime.

It is a super-2 number, since 2×660909101581² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660909101381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 746460 + ... + 1370773.

It is an arithmetic number, because the mean of its divisors is an integer number (82909824823).

Almost surely, 2^660909101581 is an apocalyptic number.

660909101581 is the 469365-th hex number.

It is an amenable number.

660909101581 is a deficient number, since it is larger than the sum of its proper divisors (2369497003).

660909101581 is a wasteful number, since it uses less digits than its factorization.

660909101581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2118351.

The product of its (nonzero) digits is 116640, while the sum is 46.

The spelling of 660909101581 in words is "six hundred sixty billion, nine hundred nine million, one hundred one thousand, five hundred eighty-one".