661973760 has 216 divisors, whose sum is σ = 2617873440. Its totient is φ = 151289856.

The previous prime is 661973731. The next prime is 661973779. The reversal of 661973760 is 67379166.

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 76536 + ... + 84744.

Almost surely, 2^661973760 is an apocalyptic number.

661973760 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 661973760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1308936720).

661973760 is an abundant number, since it is smaller than the sum of its proper divisors (1955899680).

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

661973760 is a wasteful number, since it uses less digits than its factorization.

661973760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8243 (or 8226 counting only the distinct ones).

The product of its (nonzero) digits is 285768, while the sum is 45.

The square root of 661973760 is about 25728.8507322033. The cubic root of 661973760 is about 871.5258202471.

The spelling of 661973760 in words is "six hundred sixty-one million, nine hundred seventy-three thousand, seven hundred sixty".