661826441824660 has 192 divisors, whose sum is σ = 1641721904234496. Its totient is φ = 219310976102400.

The previous prime is 661826441824643. The next prime is 661826441824661. The reversal of 661826441824660 is 66428144628166.

It is a junction number, because it is equal to n+sod(n) for n = 661826441824592 and 661826441824601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661826441824661) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 45451983780 + ... + 45451998340.

It is an arithmetic number, because the mean of its divisors is an integer number (8550634917888).

Almost surely, 2^{661826441824660} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661826441824660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (820860952117248).

661826441824660 is an abundant number, since it is smaller than the sum of its proper divisors (979895462409836).

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

661826441824660 is a wasteful number, since it uses less digits than its factorization.

661826441824660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27302 (or 27300 counting only the distinct ones).

The product of its (nonzero) digits is 127401984, while the sum is 64.

The spelling of 661826441824660 in words is "six hundred sixty-one trillion, eight hundred twenty-six billion, four hundred forty-one million, eight hundred twenty-four thousand, six hundred sixty".