661195440 has 160 divisors (see below), whose sum is σ = 2397465600. Its totient is φ = 167028480.

The previous prime is 661195411. The next prime is 661195471. The reversal of 661195440 is 44591166.

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

It is a junction number, because it is equal to n+sod(n) for n = 661195395 and 661195404.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32985 + ... + 49095.

It is an arithmetic number, because the mean of its divisors is an integer number (14984160).

Almost surely, 2^661195440 is an apocalyptic number.

661195440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661195440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1198732800).

661195440 is an abundant number, since it is smaller than the sum of its proper divisors (1736270160).

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

661195440 is a wasteful number, since it uses less digits than its factorization.

661195440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16152 (or 16140 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 661195440 is about 25713.7208509387. The cubic root of 661195440 is about 871.1841188888.

The spelling of 661195440 in words is "six hundred sixty-one million, one hundred ninety-five thousand, four hundred forty".