661042540 has 24 divisors (see below), whose sum is σ = 1448546400. Its totient is φ = 252920448.

The previous prime is 661042537. The next prime is 661042561. The reversal of 661042540 is 45240166.

It is a super-3 number, since 3×661042540³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661042499 and 661042508.

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 7 ways as a sum of consecutive naturals, for example, 718065 + ... + 718984.

It is an arithmetic number, because the mean of its divisors is an integer number (60356100).

Almost surely, 2^661042540 is an apocalyptic number.

It is an amenable number.

661042540 is an abundant number, since it is smaller than the sum of its proper divisors (787503860).

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

661042540 is a wasteful number, since it uses less digits than its factorization.

661042540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1437081 (or 1437079 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 661042540 is about 25710.7475581711. The cubic root of 661042540 is about 871.1169605708.

It can be divided in two parts, 66104 and 2540, that added together give a square (68644 = 262²).

The spelling of 661042540 in words is "six hundred sixty-one million, forty-two thousand, five hundred forty".