20531609 has 8 divisors (see below), whose sum is σ = 24699840. Its totient is φ = 16672176.

The previous prime is 20531603. The next prime is 20531657. The reversal of 20531609 is 90613502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20531609 - 2⁴ = 20531593 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20531603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77054 + ... + 77319.

It is an arithmetic number, because the mean of its divisors is an integer number (3087480).

Almost surely, 2^20531609 is an apocalyptic number.

It is an amenable number.

20531609 is a deficient number, since it is larger than the sum of its proper divisors (4168231).

20531609 is a wasteful number, since it uses less digits than its factorization.

20531609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154399.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 20531609 is about 4531.1818546600. The cubic root of 20531609 is about 273.8257767885.

The spelling of 20531609 in words is "twenty million, five hundred thirty-one thousand, six hundred nine".