661509432 has 96 divisors (see below), whose sum is σ = 1819116000. Its totient is φ = 217147392.

The previous prime is 661509427. The next prime is 661509451. The reversal of 661509432 is 234905166.

It is a happy number.

661509432 is a `hidden beast` number, since 6 + 615 + 0 + 9 + 4 + 32 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1962768 + ... + 1963104.

It is an arithmetic number, because the mean of its divisors is an integer number (18949125).

Almost surely, 2^661509432 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 661509432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (909558000).

661509432 is an abundant number, since it is smaller than the sum of its proper divisors (1157606568).

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

661509432 is a wasteful number, since it uses less digits than its factorization.

661509432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685 (or 678 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 661509432 is about 25719.8256603734. The cubic root of 661509432 is about 871.3220012444.

The spelling of 661509432 in words is "six hundred sixty-one million, five hundred nine thousand, four hundred thirty-two".