661913440 has 48 divisors (see below), whose sum is σ = 1589429520. Its totient is φ = 260421120.

The previous prime is 661913419. The next prime is 661913443. The reversal of 661913440 is 44319166.

It is a junction number, because it is equal to n+sod(n) for n = 661913396 and 661913405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661913443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24150 + ... + 43669.

It is an arithmetic number, because the mean of its divisors is an integer number (33113115).

Almost surely, 2^661913440 is an apocalyptic number.

It is an amenable number.

661913440 is an abundant number, since it is smaller than the sum of its proper divisors (927516080).

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

661913440 is a wasteful number, since it uses less digits than its factorization.

661913440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67895 (or 67887 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 34.

The square root of 661913440 is about 25727.6784805781. The cubic root of 661913440 is about 871.4993478814.

The spelling of 661913440 in words is "six hundred sixty-one million, nine hundred thirteen thousand, four hundred forty".