661740009 has 48 divisors (see below), whose sum is σ = 1058578560. Its totient is φ = 360138240.

The previous prime is 661739987. The next prime is 661740071. The reversal of 661740009 is 900047166.

It is a happy number.

It is not a de Polignac number, because 661740009 - 2⁹ = 661739497 is a prime.

It is a super-2 number, since 2×661740009² = 875799679022640162, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661240009) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 1571619 + ... + 1572039.

It is an arithmetic number, because the mean of its divisors is an integer number (22053720).

Almost surely, 2^661740009 is an apocalyptic number.

It is an amenable number.

661740009 is a deficient number, since it is larger than the sum of its proper divisors (396838551).

661740009 is a wasteful number, since it uses less digits than its factorization.

661740009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578 (or 549 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 661740009 is about 25724.3077457878. The cubic root of 661740009 is about 871.4232260419.

The spelling of 661740009 in words is "six hundred sixty-one million, seven hundred forty thousand, nine".