661651760 has 160 divisors (see below), whose sum is σ = 1970445312. Its totient is φ = 200586240.

The previous prime is 661651751. The next prime is 661651777. The reversal of 661651760 is 67156166.

It is a super-2 number, since 2×661651760² = 875566103022195200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 226469 + ... + 229371.

Almost surely, 2^661651760 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 661651760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (985222656).

661651760 is an abundant number, since it is smaller than the sum of its proper divisors (1308793552).

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

661651760 is a wasteful number, since it uses less digits than its factorization.

661651760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2971 (or 2965 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 38.

The square root of 661651760 is about 25722.5924043437. The cubic root of 661651760 is about 871.3844869369.

The spelling of 661651760 in words is "six hundred sixty-one million, six hundred fifty-one thousand, seven hundred sixty".