661444074720 has 576 divisors, whose sum is σ = 2660681447424. Its totient is φ = 147519221760.

The previous prime is 661444074689. The next prime is 661444074737. The reversal of 661444074720 is 27470444166.

It is a happy number.

661444074720 is a `hidden beast` number, since 6 + 614 + 4 + 4 + 0 + 7 + 4 + 7 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 63212209 + ... + 63222671.

It is an arithmetic number, because the mean of its divisors is an integer number (4619238624).

Almost surely, 2^661444074720 is an apocalyptic number.

661444074720 is a gapful number since it is divisible by the number (60) 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 661444074720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1330340723712).

661444074720 is an abundant number, since it is smaller than the sum of its proper divisors (1999237372704).

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

661444074720 is a wasteful number, since it uses less digits than its factorization.

661444074720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10815 (or 10804 counting only the distinct ones).

The product of its (nonzero) digits is 903168, while the sum is 45.

The spelling of 661444074720 in words is "six hundred sixty-one billion, four hundred forty-four million, seventy-four thousand, seven hundred twenty".