661511101644 has 144 divisors (see below), whose sum is σ = 1777561225440. Its totient is φ = 215370441216.

The previous prime is 661511101613. The next prime is 661511101661. The reversal of 661511101644 is 446101115166.

661511101644 is a `hidden beast` number, since 6 + 6 + 1 + 5 + 1 + 1 + 1 + 0 + 1 + 644 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 661511101599 and 661511101608.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16154604 + ... + 16195500.

Almost surely, 2^661511101644 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 661511101644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (888780612720).

661511101644 is an abundant number, since it is smaller than the sum of its proper divisors (1116050123796).

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

661511101644 is an equidigital number, since it uses as much as digits as its factorization.

661511101644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41008 (or 40945 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 661511101644 in words is "six hundred sixty-one billion, five hundred eleven million, one hundred one thousand, six hundred forty-four".