20687009 has 4 divisors (see below), whose sum is σ = 23642304. Its totient is φ = 17731716.

The previous prime is 20686969. The next prime is 20687027. The reversal of 20687009 is 90078602.

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 a de Polignac number, because none of the positive numbers 2^k-20687009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20687039) 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, 1477637 + ... + 1477650.

It is an arithmetic number, because the mean of its divisors is an integer number (5910576).

Almost surely, 2^20687009 is an apocalyptic number.

It is an amenable number.

20687009 is a deficient number, since it is larger than the sum of its proper divisors (2955295).

20687009 is an equidigital number, since it uses as much as digits as its factorization.

20687009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2955294.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20687009 is about 4548.2973737433. The cubic root of 20687009 is about 274.5148868893.

The spelling of 20687009 in words is "twenty million, six hundred eighty-seven thousand, nine".