661913600 has 114 divisors (see below), whose sum is σ = 1657795494. Its totient is φ = 262144000.

The previous prime is 661913599. The next prime is 661913611. The reversal of 661913600 is 6319166.

It can be written as a sum of positive squares in 3 ways, for example, as 177209344 + 484704256 = 13312^2 + 22016^2 .

It is a super-2 number, since 2×661913600² = 876259227729920000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6553550 + ... + 6553650.

Almost surely, 2^661913600 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 661913600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (828897747).

661913600 is an abundant number, since it is smaller than the sum of its proper divisors (995881894).

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

661913600 is an frugal number, since it uses more digits than its factorization.

661913600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 108 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 661913600 is about 25727.6815900695. The cubic root of 661913600 is about 871.4994181020.

The spelling of 661913600 in words is "six hundred sixty-one million, nine hundred thirteen thousand, six hundred".