661582009 has 4 divisors (see below), whose sum is σ = 721725840. Its totient is φ = 601438180.

The previous prime is 661582007. The next prime is 661582039. The reversal of 661582009 is 900285166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661582009 - 2¹ = 661582007 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661582003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30071899 + ... + 30071920.

It is an arithmetic number, because the mean of its divisors is an integer number (180431460).

Almost surely, 2^661582009 is an apocalyptic number.

It is an amenable number.

661582009 is a deficient number, since it is larger than the sum of its proper divisors (60143831).

661582009 is a wasteful number, since it uses less digits than its factorization.

661582009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60143830.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 661582009 is about 25721.2365371496. The cubic root of 661582009 is about 871.3538655542.

The spelling of 661582009 in words is "six hundred sixty-one million, five hundred eighty-two thousand, nine".