661385900 has 72 divisors (see below), whose sum is σ = 1643748960. Its totient is φ = 226275840.

The previous prime is 661385897. The next prime is 661385911. The reversal of 661385900 is 9583166.

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, 512456 + ... + 513744.

Almost surely, 2^661385900 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 661385900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (821874480).

661385900 is an abundant number, since it is smaller than the sum of its proper divisors (982363060).

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

661385900 is a wasteful number, since it uses less digits than its factorization.

661385900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2043 (or 2036 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 661385900 is about 25717.4240545199. The cubic root of 661385900 is about 871.2677602188.

The spelling of 661385900 in words is "six hundred sixty-one million, three hundred eighty-five thousand, nine hundred".