661225920 has 56 divisors (see below), whose sum is σ = 2099395344. Its totient is φ = 176326656.

The previous prime is 661225883. The next prime is 661225967. The reversal of 661225920 is 29522166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 343429 + ... + 345348.

Almost surely, 2^661225920 is an apocalyptic number.

661225920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661225920 is an abundant number, since it is smaller than the sum of its proper divisors (1438169424).

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

661225920 is a wasteful number, since it uses less digits than its factorization.

661225920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688797 (or 688787 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 661225920 is about 25714.3135237945. The cubic root of 661225920 is about 871.1975053916.

The spelling of 661225920 in words is "six hundred sixty-one million, two hundred twenty-five thousand, nine hundred twenty".