661604040 has 48 divisors (see below), whose sum is σ = 2150214300. Its totient is φ = 176427648.

The previous prime is 661604033. The next prime is 661604081. The reversal of 661604040 is 40406166.

661604040 is a `hidden beast` number, since 6 + 616 + 0 + 4 + 0 + 40 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 607228164 + 54375876 = 24642^2 + 7374^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661603995 and 661604013.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 918535 + ... + 919254.

Almost surely, 2^661604040 is an apocalyptic number.

661604040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661604040 is an abundant number, since it is smaller than the sum of its proper divisors (1488610260).

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

661604040 is a wasteful number, since it uses less digits than its factorization.

661604040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1837806 (or 1837799 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 661604040 is about 25721.6647983757. The cubic root of 661604040 is about 871.3635376148.

The spelling of 661604040 in words is "six hundred sixty-one million, six hundred four thousand, forty".