661603920 has 40 divisors (see below), whose sum is σ = 2050972896. Its totient is φ = 176427648.

The previous prime is 661603903. The next prime is 661603937. The reversal of 661603920 is 29306166.

It is a happy number.

661603920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (661603903) and next prime (661603937).

It is a tau number, because it is divible by the number of its divisors (40).

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, 1378102 + ... + 1378581.

Almost surely, 2^661603920 is an apocalyptic number.

661603920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661603920 is an abundant number, since it is smaller than the sum of its proper divisors (1389368976).

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

661603920 is a wasteful number, since it uses less digits than its factorization.

661603920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2756699 (or 2756693 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 33.

The square root of 661603920 is about 25721.6624657117. The cubic root of 661603920 is about 871.3634849329.

The spelling of 661603920 in words is "six hundred sixty-one million, six hundred three thousand, nine hundred twenty".